If you to keep the princess look, try a princess cut channel band.  I think that might inhance your engagement ring.  But if you want to go crazy, go with the "round & square" look and get a prong set round diamond band.  It sits up high, so you will have to have your ring high measured.  Good luck

Thanks, Robin. I actually tried one on this weekend and it was a channel set princess cut ring. It did enhance my ring, just like you said. It was even much smaller than I thought I would want but the two together just sparkled like crazy! I think that will be the winner, but I'll definitely try on one of the prong set round rings just to see ;)

Thanks again!