There's a new pattern coming out soon with the yarn weights variations too - Looking Glass Longies by Kelly Brooker. I just knit a test pair for her and it's a fairly good pattern, uses provisional caston to avoid grafting the crotch - I don't mind grafting though (infact I quite like it).

I've done a few pair of longies so far - even though we aren't using them ourselves anymore lol. I really enjoy knitting them, so now I have to just knit them for others.