Wire floors and levels are actually just fine and much more sanitary for rats. Just be sure to offer them hammocks, boxes, and other solid things for them to rest on. If your rats are on solid floors they will be sitting in puddled urine and feces and *that* can actually cause bumblefoot (infection on the bottom of the rear feet). Martins Cages are definitely the favorite amongst rat enthusiasts. A few other links to help you along:
Rats Rule! Forum
http://www.goosemoose.com/component/...,118/forum,rat
RatPalace Forum
http://www.ratpalace.com (click on Discussion Forums)
Rat Health Guide
http://www.ratguide.com
A ton of helpful links:
http://home.interlog.com/~audiotre/rats/