Four of us will be arriving at BKK airport and I am not sure which would be the most convenient way to get to hotel. I guess that it will be imposible to go on an only taxi...
Which would be the best option then? Two taxis? A limousine? Is there any possibility of hiring a minivan taxi?
And what about prices?
Our group could even increase to 6 people (if my brother and his wife get a good flight) and I am a bit worried.
Thanks.

You can take two taxis (or three if there are 6 of you). The Limos are really just large sedans, and wouldn't carry 4 adults. There are no minivan taxis, but some of the limo services do have minivans.

The Thai limo service does have minivans. Actually, there are even some taxis using small vans and converted pickups these days.

If you want to be absolutely certain of getting a single vehicle transfer, you can try booking in advance. This page has links to places where you can book Bangkok airport transfers:

http://thailandforvisitors.com/centr...l/gethere.html

just yesterday i received an e mail from this company and they offer vans:

www.airporttransportthai.com

Yes, you can get a mini van. We had one our last time in BKK because there were four of us plus bags. We walked past the taxi drivers to find the van service though. I wish I could tell you the name of the company. Sorry...

So the van seems to be the best option...
Thank you very much.