Going to conferences: all the research team members together or everyone alone?
If I 


had the time, and 
had the money,


I would go to every conference directly related to my field that I could.  They are a fantastic way to find out where the tip of the spear is in your field, to network and meet new people, and to see parts of the world you might not be able to see otherwise.  Additionally, many conferences have workshops, expos, and special speakers that all add to one's professional development.

Why do I bring all that up?  Most, if not all of the time, it is professionally advantageous for everyone involved with a paper to attend conferences.  Practically, this rarely happens (at least in my field), simply because funds can't support it, and time commitments make it difficult to travel to various parts of the world.

So, my answer is, send as many people as can practically afford to go, because they will almost certainly gain from the experience.