Personally, I would use Seaweed+Snow, because you can also get the Pearl dragon while it is still in the market. But, that also runs the risk of the Rainbow dragon, which is an excruciating 2 days to breed/hatch.
I got my first one with Scorch+Seaweed, then i bred Rainbow+Leapyear to get my second Rainbow, but i got a second Leapyear instead. Then i tried for Ruby (Scorch+Chrome), but i got my third Leapyear. I was pretty surpried about that :D
Lol, I made this discussion just for fun, I didn't think it'd get so many comments. I have already gotten the Leap heap so I'm satisfied. I've been working on the solstice and all th gemstone dragons, I have all but garnet and turquoise, I just got my THIRD solar eclipse trying for the garnet........ugh......and now I got another equinox..UGH!!!!!!!!!
You many use any 4 elemnts to breed a leap year (though the chances are ptetty low of obtaining one). But since the LYD is expired you'll have to wait until it returns at the next leap year (Late February 2016).