I think a hat would be a great project to do next.
Just make sure if you do pick a project in the round to do - maybe do a project that is mainly on a circular needle, rather than double pointed needles. DPN's are a bit trickier to get.
If you choose a hat, you'll mainly use a circular needle, and then at the very end you'd use the dpn's for the very top of the hat. It wuld give you some exposure with dpn's but without being too much of a pain.
And, knitting with circular needles is a ton of fun! Just remember that you're always working on the same side of the work... so instead of knitting and purling to get stockinette (knitting ont he right side, purling on the wrong side), you would just keep knitting.
Let us know what you decide to do!