If I can only bring one instrument to a session, I bring a Sadowsky MV5. I got it only recently but it has quickly become my main bass. I don't have any sound samples of it yet. Before I got the Sadowsky, I used a Fodera Edward 6 for most everything. It covers a lot of ground. It provides many shades of modern and vintage tones with relative ease. I have some samples of it on my myspace page (click the myspaz link in my sig). I used it on the first, second and fourth tracks. There are even more songs on my iComp page (with detailed tech notes about the recording):
http://www.icompositions.com/elmaestro
Before that, I used a 1990 Smith BT6 a lot. I used it on
The Yards' latest release, Wit. You can check out some samples of that record here:
http://www.hammondbeat.com/hammondbe...se&k=34&r=1541
All three of them have distinct voices and sit in the mix in a special way. When in doubt, I bring the Sadowsky and the Fodera in a double gig bag. I also have two Fenders that I use. One's a '62 RI Jazz and the other is a '57 RI Precision. Both have Lindy Fralin standard vintage pickups. For special sounds, I also occasionally use a '70's Hofner 5000/1 Deluxe, an F Bass BNF5 and a Tacoma Koa ABG.
*Side note*
I used to think the best way to get my sound to tape was to either use my live EQ settings (bad idea) or at the very least, cut some highs. What I didn't realize is that when you record it and mix it down (or bounce it down), some of the high-frequency information that gets lost in the process. Nowadays I record with a little more highs than I like (no roll-off but no treble boost) and by the time the mix is done, it usually sounds the way I expect it to.