I would recommend spending some time on one of the nissan forums, a quick
google search turns up many. You can browse pictures of other people wheels or request pics from members. Wheel appearance is very subjective, so you want a wheel that performs good but also looks good to you. When looking for wheels, you want something lightweight and forged.
Looks like an 18 with a low profile tire will look good and fill up the wheel gap nicely, as well as give you better road handling. However, if you are serious about handling, you may be looking for some struts and springs or coilovers later. A drop in the cars ride height may cause rubbing with 18's, so a 17 might be a better option. Check the nissan forums for best size to go with, also the depth (7", 7.5", 8") and the correct offset. Once you know what you need, check out
Tire Rack for a good wheel and tire combo deal.
Dunlop, Bridgestone, Pirelli and Kuhmo all make good mid-level performance tires that offer good road handling, long life and cheap price. If you want a summer ultra high performance tire, be ready to spend $1000+ on tires alone and they will wear very quickly. A SE-R is a nice car (I thought about buying one before), but not really a likely candidate for such a tire. You can do tires and all the suspension mods you want, but it will still be front wheel drive.