Anyone who is doing/has done commerce apps/sites: I need your help.

[Jeff Hadfield]

We have an Unnamed Major Client who would like to hear about your experiences in choosing commerce tools/providers. For now, you would talk (email, Skype, whatever) just to me and we'll pass your comments and experience along to the client. I'd like to talk to you about your overall process -- how did you decide what you needed, how did you narrow down possible solutions (APIs, services, etc.), and how did you choose one? Then, what was your experience in implementation and maintenance -- and what would you tell a Major Provider if you had the chance to do so? If you have a few moments, I'd appreciate it.