If you really just play guitar for song writing and to improve your bass playing a good small cheap modeling amp is a great thing to have.
Japanese built 12 string strat. I got this primarily because I wrote a 12 string guitar song to honor my grandfather's passing. Nice Guitar but really a flavor or the month.
Fender Custom Shop Telecaster. Need I say more?!
Ibanez Iron Label S series. I always loved the S series because of the thin neck and body. But always wanted a hard tail. They'll finally delivered.
Learning to play guitar makes you a better bass player. Especially learning the chords. The more chords you learn on the guitar the more you will visually be able to identify what a guitarist is playing. This allows you to follow the guitarist with greater ease. Every bass player should first learn the open chords, then the bar chords, then the jazz chords. Your band mates will love you for it. Of course sometimes your guitar player might get a little intimidated by the bass player who can identify the chords he is playing when he himself can not. In such situations I try to soften the blow to the guitarist's ego by explaining that Stevie Ray Vaughan didn't know how to read music. We all know how sensitive the guitarists can be. Especially the one's who pretend their the alpha male and band leader. It's also good to have some guitar skill just for song writing as well.