So, I am making a world for The Sims 3 of a large city and its surrounding environment and don't know what to do with some of it!

My map is on an altered LargeFlatMap100 with a Max Height of 300.
With this, I made a river going north/south just to the east of the center and mountains to the north, west, and south. The city is in the middle, uses the Late Night bridge to cross the river, and has highways running through the northern and western mountains. There is a lake in the south-west part of the mountains.

Below are screenshots of the map so far.
The light-colored grid-like pattern is a suburban residential zone. Downtown is in the middle. On the other side of Downtown is an industrial zone. The mountains will be forested with some more houses, country stores, and even some "hangout" lots (probably for Sims from Supernatural). My biggest issue is with the other side of the river. What to do here...
I have considered three options, but of coarse each one has its issues.
1: The ocean
a. The good thing here is it would provide a great view during sunset (or rise, or whatever)
b. The bad thing is that I would be able to have that bridge, which is supposed to be part of the city's skyline
2: Farms
a. The good thing is that this could also provide a good view (if done right).
b. The bad thing is that there is not enough room for any kind of border mountains between farms and where the map just drops off into endless ocean.
3: Forests
a. The good thing is that the edge of the map will be harder to see with many trees everywhere
b. The bad thing is that, for one, there won't be much room for any kind of useful road here, which means no bridge... and two, won't provide much of a view from downtown.

So, what do you think I should do here?

Also, I have heard that 150 lots is about what most computers can handle, but my map has 280 and I haven't noticed any issues yet. So, just out of curiosity, does anyone here know if they have a "limit" before the game starts to act up? If so, what is it? 100 lots? 150? 300? Also, is this a processor issue (something to do with RAM), graphics card related, etc? I have 8GB of RAM (usually about 4GB are free at all times) and an NVidea GeForce GT660 card. I ask this because I do plan to release this world and would like for people to actually be able to play it.

First, a disclaimer: I am a total CAW newbie and am also just now building my first world. Therefore, I have no idea about the number of lots. I have a pretty beefy gaming laptop, and the largest city I play is Praaven (which is massive and still runs with 45-60 fps on highest graphics settings), but I really don't know how many lots it has. Hopefully, someone else can help with this part.

As far as what to do with the empty bit of your world, my vote would be beaches with a row of skyscrapers along the river edge so that the bridge can still be part of your skyline. There are plenty of coastal cities with skyscrapers almost right up to the edge, so I don't think it will look too odd. Take this picture of Rio, for instance, which has a terrain similar to your town:

I do think you need some variety in your terrain paints, though. Flat green doesn't look very realistic, and is also bland. I think you especially need to take another look at the terrain by the lake. Grass won't grow on the steeper areas, and it won't grow right on into the lake, either. Try adding some exposed rock on the steeper areas, and maybe flatten parts of the terrain by the lake so your sims have a nice beach to enjoy.

I also see some areas where your roads run right over the tops of hills. Roads are not built this way. Instead, they snake around the hills, using switchbacks to climb where necessary. I don't know how well sims will or won't use your steep roads, but it does look a bit jarring, in my opinion.

Hope this has helped

Edited, sorry.

@bobgrey1997 150 is a good number for lots (if you want to make this world look like a big city, you can use big lots with many constructions, like São Paten

@AndreaJEP The city in this picture is Rio de Janeiro, not São Paulo. Here's an actual picture of São Paulo (that's non-coastal and mostly flat)

Also, I'm brazilian

@MW_thesism3 I meant to say Rio, sorry! I was also reading through the Sao Paten thread while posting here and my wires got crossed. The hills of "Auburn City" reminded me of the Sugar Loaf.

It's okay! I've saw much more rude fails related to Brazil, like this :D

The images won't load for me, but I see from the first comment on that page what the problem is with them, let alone the poll itself! My mom is from Brazil, too, actually. She lived in Paraná until her teens.

I read the thread for the Sao Paten map and noticed the island chain to the east. Prehaps, I could do that by making the highway cross the bridge and curve south with the island chain, and either end or bridge off into more "distant islands" off the map... This would leave the downtown and (formerly) River Market (now being something like coastal promenade) with a good coastal view, could place some high-price tropical lots on the islands...
That sounds good, so I just might do it! Unless of coarse, anyone wants to post some suggestions that I haven't heard or thought of... That is always welcome!

AndreaJEP: About the terrain paints; yeah, I know. This is still in (extreme) early development.
Also, the roads may look like they are steep from certain angles, but none of them are steeper than 45 degrees (which is VERY steep, but still climbable in lower gears) which I think is still much steeper than the steepest road here. They do quite a bit of "snaking". I do, however, have several places where the road "cuts" through the hill, creating a "trench" or "gap" in it. In these places, I intend to put rocks on the sides to look like the hill was carved through to make room for the road. Similar to what you see in this picture where the highway goes through a rock arch.
The Sims don't react to the road's grade though as they treat roads as flat paths. The routing of roads and sidewalks, from what I can tell, override the maps automatic routing from water and hills and can only be affected (if at all) by manual routing via the routing painter tool.

MW_thesism3: After playing a New York map, I noticed they used "deco(rative) buildings" which are just textured objects that have no interactions or interiors to give the feel of a dense city without the lag of many lots. This, as well as grouping structures on lots, would be great for a downtown area, most of my lots are in suburban areas where you have many single, detached, houses within about 10 feet of each other. Placing these together on the same lots will cause multiple families to get confused and walk into each other's houses. The only way to fix this would be to use door locks, but then, inviting guests to these houses will be troublesome...

The world certainly looks interesting so far. For the uncertain space across the bridge, I'd vote for more woodland/forest.
One thing I have noticed is that you may get some routing errors/issues where you have the road going directly under the bridge. You may end up with sims and cars accessing the bridge via the road that goes underneath it, i.e. driving under it and then teleporting up onto it, rather than driving up the ramp that leads to it. The game can be a bit weird with stuff like this.

I know that bridges in this game do work oddly. For example, the smaller bridges that link the Downtown area to the Industrial Park do not allow routing of house boats under them, but the Late Night bridge is supposed to allow house boats to go under it. I would assume this should work for roads as well.

Thank you for pointing this out. Now I will go test this...

Edit: Yeah, this road under the bridge thing is out the window... Unfortunate... I was going to place a lot with a junkyard under there just because I think I could use the bridge's support girders as part of the lot and make it look amazing, but oh well...