Sig Somthin Extra. Both the kit and the ARF fly great. Excellent sport and aerobatic airplane: http://www3.towerhobbies.com/cgi-bin...?&I=LXZL44&P=0

The Great Planes Revolver is definitely not a slow plane but it is a sweet flyer with the .55-AX: http://www3.towerhobbies.com/cgi-bin...?&I=LXRWV9&P=0

Another option is the Hangar-9 Twist. It is very aerobatic but can float around at a crawl if you want: http://www.horizonhobby.com/Products...ProdID=HAN2650

If you want to try something more scale the Pawnee will fly great with the .55: http://www.horizonhobby.com/Products...ProdID=HAN4030

The U-can do is also a fun plane but just keep the speeds down. Go too fast and it will shred itself into a pile of balsa splinters.