I have one buddy who I rarely hangout with, were both pretty busy and have girlfriends and stuff but whom I can pickup the phone and would drop what he was doign to come help me with something and vice versa. I can talk to him about serious stuff, ask him for advice, etc. The rest of my "friends" are more casual acquantances who would break plans last minute the second something better came up to do. I find a lot of people are like that these days but like you said if you find a good friend keep them around.