You say that 17"+ rims are out, but were you planning to go with another 15" rim or jump up to 16"? As a general rule, all aftermarket rims (especially cheaper ones like Motegi and pretty much anything on eBay!) will be softer and "weaker" than stock rims, which I found out by bending a rim and puncturing a tire that was less than a week old. Exceptions to this 'rule' are some of the higher-end wheels. BBS comes to mind. I'm sure you will find many conflicting opinions about this, but I share what I've been told by so-called professionals and some of my personal experience.
As for tires, I've had great success with Toyo Proxes4's for a high-perf tire.They grip like stink in wet or dry, wear good (I have about 15K on my civic, at about 1/2 wear), are not too expensive (~$70ea), and best of all, track better in standing water than any tire I've ever used. Highly recommended. Just remember to run them at the max pressure (50 I think?) to protect the rims if you go aftermarket.
If you want a longer-life, more comfy 'touring'-type tire, I like the Yokohama Avid H4's. My wife has them on her '01 Avalon, and they are great. Grip is not an issue in a car like the Avalon, but the ride is super quiet and smooth. The treadlife seems to be pretty good also. She's got about 20-25K on them and they are about 75% worn. I'll be replacing them in the next few months.
I hope this helps. Use the tire size calc mentioned above, and check out
http://www.tirerack.com and
http://www.discounttiredirect.com for good research tools.
Cheers!