Like David, I also like the look of striped ties with kilts. Solid also is a good choice, though. I own and wear both kinds.

I find that these days solid color ties are getting harder to find in a lot of menswear stores, especially in good colors that might compliment your kilt.

We sell solid lambswool ties made by Lochcarron, in colors specifically chosen to compliment most tartans. See:
http://giftshop.scottishtartans.org/ties.html