Lots of ideas her so I thought I'd add my 10p worth.  I had a lot of trouble recording bass, I tried DI and mic.  I had the sound I wanted from the amp but found it aounded very different when recorded and placed in the track.  The things I found out after many failures was as follows:
1  The bass in the track is very different from the bass you hear on its own i.e. what sounds like a great bass sound is often shite when in the track.  Conversely a clicky buzzy apparently top heavy sound ofen changes completely when listened to with the rest of the track.
2  I always make sure before recording that I have some EQ sensitivity in the mid range sweep with the sound from source without worrying too much about how it sounds at that time.  I found that the bass players normal sound used live had no real 150Hz ish 300Hz component so when it came to EQs during mixing I had no ability to change the sound in this range.  The bass sounded 'woolly' with no real desinition whan placed in the track.  I did this by asking the bass player to adjust the knobs on his bass until a mid sweep made some real difference to the sound.  I think this is what Sjoko2 means?
3  Very small changes to the mic position has a profound affect on the recoreded sound (by very small I mean 1-2").  I found it so difficult to get this right that I abandoned using mics on their own and use a combination of direct into the desk and mics.  I try to get as clicky a sound as possible from the mic.  (Someone on this BBS had a link to an article about recording Chuck Rainey where they recorded the sound of his bass by close micing his fretboard it was a good article but i dont have the link anymore)
4  I use some compression to get control of the source as I'm recording to digital HD but try not to colour the sound.  THe only time I added more was when I had a tune that had slap and finger style techniques but this was not entirely succesfull.
5  For a quick fix I use a J Station.  This is the most usefull single £100 box I have.  I can get better results with mic and DI and lot of effort but this does a great slap / fingerstyle combination.  I used this on "I feel for you" 
www.nowhereradio.com/mobounce/singles 
if you're interested.
Just my thoughts, I am no expert, the above has been discovered after many failed attempts.