Our band is changing more and more into an instrumental one. Our bass player left, I'm playing bass now and so no one's singing anymore, as I can't do all at the same time as a complete bass newbie

So it's definitely time to add some fatness and melodies to our sound for supporting the guitars (like nice warm and full stereo pads or leads), or even replace the bass with a synth. As most of you out there are synth fanatics, I'm quite sure you can recommend me something fat. for the ones who don't know me and my music, have a listen here to get an impression (live recording from a jam lately, it's raw, don't blame me for the quality

http://www.alterhistory.com/music/alterhistory-jam1.mp3
http://www.alterhistory.com/music/alterhistory-jam2.mp3
old Songs: http://www.mx3.ch/artist/alter_history
I tried all synths from my library but wasn't quite pleased with them, they just don't really sit well in our music. Ah, I've got all synths except the ones from John Bowen... And as it's christmas sales now, i'd maybe go for a Bowen one. Which one would you recommend?
Any input appreciated!
Cheers
Roman