12 Y.O. Litespeed MTB, IRO Jamie Roy fixie, Custom Habanero Ti 'Cross, No name SS MTB, Old school lugged steel track bike (soon)
If you can afford it, get a second set of wheels. I have one set with beefier rims and a 13-30t stack and 32c knobbies for dirt, and another set with light rims, 26c slicks, and a 12-21t stack. It's great to be able to switch wheels in a matter of seconds, depending on what I want to do that day.
Still, all you really need are a pair of decent road tires. The cross gearing is fine.
Cannondale SuperSix, Lemond Poprad. Retired: Jamis Sputnik, Centurion LeMans Fixed, Diamond Back ascent ex
I ride a stock Lemond Poprad with 25c tires (46/38 chainrings, 12-26 cassette). With these tires/gearing I have no problem riding in groups at 28-30mph. Haven't done downhills, but even with 46/12 one should be able to spin up to 35-40mph.