Well, the first thing you have to ask yourself is, "Why do I want this server?". Is it to fullfill a personal dream? Or, to provide a service to the community? Or, to get an experimentation ground(for insims, or else).
The thing is, there are a lot more servers than players. Right now, as I type, there are 612 servers for "only" 692 online players. 540 of them are empty, which represents approximately 88%.
I don't want to be a Debbie Downer, but if you don't have a very solid plan behind this, your server will join those 88% straight away. And you don't want to waste your time and your money, do you?
If you want to be successful, you need to find THE thing that will make drivers join your server instead of others. Because, they litterally have hundreds of other servers to go racing for free, and they won't go at yours just for sympathy.
And, let's not forget, building successful servers out of no strong community is an almost impossible task. You could come up with the perfect idea, the perfect insim, and the perfect adminning system, and still end up missing the most important thing: the drivers. You need to have a devoted "fanbase" racing on your server as often as possible, to keep it as high as possible on the server list, so you can make the server attractive to average Joe's like me.
There are plenty of servers that ended being "one hit wonders", because for whatever reason, they couldn't attract the racers for more than a few days or a few weeks. I recall in particular of EQ Worry's project, which sounded perfectly fine on the paper, but ended up being a monumental flop.
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But anyway, to answer your question... I would be pretty interrested in having a sort of revival of the "CTRA Bump and Jump" server, with the old layouts. It could be an interresting idea to consider, as there are no active servers offering autocross racing at the moment. But would there be enough interrest to keep the server populated on long term? Here's the question.
Something single seaters would be nice - either MRT/FBM/FOX/FO8, or multiclass with all of them - but then there is FOX Junkies and cargame.nl's OW server and they are pretty much empty all the time, so I guess there is not enough interrest for that stuff right now.
BTW, I might be in the minority, but I'm not a big fans of servers where you have to get "experience points" or whatever you call them, in order to unlock the more powerful cars. When I fire up LFS I just want to goddamn race, not cruise for meaningless points. Keeping the unexperienced away from the dangerous cars is a necessary evil, OK, but you can just filter them with Airio's !ex index.
Well, it would be nice to see a STD Class server 
Not only the system, but also those people, who bought S2 and felt like they have their racing license in this big simulator. Like it's honor for them to race against someone better, like they already knew what danger T1 brings... And I could continue forever.
