From what I know...: Clarke Quay is way too touristy, thus price tends to be high. If you walk further down, away from Liang Court then walk across to the other side of the road, you'll land yourself in Boat Quay. I personally find the ambience slightly better than Clarke Quay. Don't expect the price to be lower though, cos it's also full of tourist.
I think you would love Zouk, lots of hip & happening youths there, I heard... There're also some nice clubs along mohammed sultan road, just off River Valley Road.
If you just want to hang out for a drink without too much noise and smoke, you can explore Holland Village. Or go up to mount Faber for a top of the 'hill' view of Singapore. Can't remember the club name though... I think it's called Altivo or something. Or hotels will have some nice lounges too, with some having prices similar to that of Clarke Quay's!
As for food, well, they're always promoting their chili crabs.. :p If you can't eat seafood (which is a pity ), and would like typical local fares, try chicken rice (Boon Tong Kee), pork rib's soup (Founders); both along Balestier Road. And for prata, the famous one is located along Jalan Kayu. For the rest (like fried kway teow, hokkien mee, popiah, etc.), you can often find them in most food courts cheaply..
But as you're based in Singapore now, the best way to find out is to discover and experiment by yourself, especially when Singapore is not so big.. Hope I've helped in some ways and have fun!!!