For a multi member acoustic gig, what are your preferred Mics and Mic patterns?

Omni?
Figure eight?

Has to work for live performance. Condenser?

http://blog.shure.com/how-to-mic-a-bluegrass-band/

I found this and thought it was good reading.

Mic for PA use or just recording?

The former will depend on the instruments used and number of people. In fact a single mic isn't a good idea for sound reinforcement unless you're sealing with an unaccompanied singer or particularly obstinate Bluegrass purists, a species thankfully rare in the UK.

For recording much would depend on where you can put the mic. On the stage, overhead, back of the room.... Also on the amount of anticipated audience noise, air conditioning hum and so on. Condensor, certainly, maybe a stereo pair, but pickup pattern and sensitivity depends on circumstances. From the back of a venue a highly directional mic might well be the best, even a shotgun, but that would be useless near the performers.

I have never done this, so this is more thinking out loud. I would probably default to a condenser used only for recording (to prevent any feedback loops), and a cardioid pattern (facing the band with the dead zone to the audience, if possible). Omni/Figure-8 would just be asking for trouble IMO (especially with "unknowns" in the picture). If using only one mic, you may also see a situation of having to position instruments for best results.
 
As tlw mentioned, many more factors come into play here, especially if you are limited to what/where you can place things.

The case is definitely for performance... acoustic rock jam in a small house where they don't want the full rig.

The question is a little outside my envelope, too, but I know that the Shure KSM-32 has been a standard at the Grand Old Opry for years. I've seen it used often for acoustic instruments, on everything from pianos to mandolins.
 
The photo in that piece is a KSM-44, but it's essentially a more expensive multi-pattern version of the KSM-32.
 
I wouldn't think an omni mike would be very practical (bleed and feedback problems), unless you wanted to do the old-school thing with multiple singers or instrumentalists gathered around one mike, Beach Boys style. However, the KSM-44 would give you the option of omni, cardiod or figure-8, plus it has two high-pass filter settings the KSM-32 doesn't have. It's also physically larger than the KSM-32, making it more obtrusive visually.
 
All in all, I think a KSM-32 might be a safe bet for miking individual instruments.

It depends on  the venue. I would never dream of using condensor mikes in a noisy pup or party on acoustic instruments. 
A quiet venue or outside and on big stages then your fine. 
In a house? I would not even use a PA if people are sitting and listening. 
But if the party is rowdy then a small PA or each player has a small amp is best. 
Condensor mikes feeback in most smaller under powered PA situations. You need more space or a more powerful system. 
This is why 90% ( just a guess) of acoustic players use electronic PU systems. There are many types and a good PU system will outperform a mike on a stand. Many of the systems include a condensor mike inside your instrument. This web site has excellent stuff at a good price. 
 
http://www.guitarfetish.c...tic-Pickups_c_443.html
 
If I do use a mike live I use an SM 57. That was our standard in many bluegrass bands I played in for the last 3 decades. 
There's just to much crap gets into condensors when there's ambient noise. They only work when the room is quiet and good acoustics like a concert hall. 
I would use built in PU's on all that have them then a SM 57 on any instruments that don't. 
They make plenty of nice small acoustic amps these days that also include a mike channel for singing. 
They are my favorite because it also does double duty as your personal monitor. 
 
 

Ditto on Johnny V's comments. I have a pal in an acoustic bluegrass band that play/sing around one AT4047 or a 4033, on a restaurant patio (off Lake Michigan) and when the wind blows you don't hear them or maybe only half of them. They like it, but in the audience it's very "iffy". When it's quiet they sound good, otherwise they are sort of lost to the noisey crowd, and when the wind blows ....forget it. It's all wind noise!
Gigging from '60s acoustically sucked! I used Barcus Berry when those came out, but they sucked too! LOL
In the '80s I used an EMG Strat pickup in the soundhole of my Guild F50 plus a pair of BB inside on the plate. I had a jack for the EMG going to an echo and a 15" JBL, while the BB's(on jack 2) went to a chorus and then the PA. That sounded really good once I got the EQ/balance worked out. Kathy Mattea once walked in front of me and stopped dead, saying, " wow! your guitar sounds great, like a grand piano!" and we talked about the rig on my break. I thought it sounded great too. LOL I got the rhythmic strum and lots of sustain-y bottom. I recorded off the PA and several engineer pals would always listen and say "there's 2 guitars! Who's playing the other one?" The affect of the piezo and the EMG captured 2 completely different flavors.
       Nowadays, there are way more options, though one mic really depends on the stage setting and then the band has to learn to work it, too.
Michael

For sound reinforcement, a single mic for the whole band is more trouble than it is worth.  You will not achieve any significant gain before feedback at the distance you would have to place it to capture everyone.
 
For a recording only, if you like mono, go ahead.  I would never dream of it.  A stereo mic like Rode NT4 would be better than nothing, or, God forbid, one of those stereo shaver recorders.   If I only could choose one mic, it would probably be a Royer SF12 or other stereo ribbon like AEA R88.  

Our group uses two Shure Super 55 microphones (http://www.musiciansfrien...5-dynamic-microphone). This is a dynamic microphone, but still picks up good. There are 5 of us in the group - all acoustic except for the bass. The mic works very well, although you sometimes have to work your instrument (for instance we have to lift up the mandolin a bit and move to the front of the mic when doing a solo). In addition to a good sound, it looks good too if you like the old style microphones!