Hi Emma,
It seems that many beautiful and proven boat designs have already been suggested in response to your query. Allow me to add one more. I have not yet completed the Cape Ann Storm LT (for my wife...135lbs, 5'4") or the Cape Ann Expedition (for myself) I purchased from Vaclav Stejskal at One Ocean Kayaks, but I did spend a good deal of time researching the various designers' web pages and decided on the these two. Now, I can't speak authoritatively on the performance of these boats since they are still under construction, but I thought his designs were a good compromise between primary and secondary stability and he is quick to answer any e-mails you send him. Extremely helpful. I can also tell you that, as a first time builder, the Cape Ann Storm LT hull was a breeze to build (no compound curves). I think One Ocean Kayaks, as well as Guillemot-Kayaks, have so many models to choose from that one of them is bound to suit your needs. I guess the other thing to remember is that, as many have told me, build a boat that will suit 90% of your paddling time, because it's almost impossible to find one design that does everything well!

Rob