Outmoded

Hello all, I'm starting to think about who I will be asking for letters of recommendation. I have a few professors that I know will be more than happy to write them, one's I've worked with before and I'm not really concerned with asking them or what they'll say. I've been working as an undergrad researcher since I was a freshman (4 years now! wow!) and have worked with, and published with, a few grad students. They have now since received their PhD and are doing very well for themselves (One is a senior researcher at Dow and another at Boston Scientific). They are people I worked with for years and know me both on a professional as well as a personal level. Is it acceptable for one of them to write a letter of recommendation and is it advised? I think that they would provide some depth to my application with a more personal letter. Is that a dumb idea and should I just stick with the professors? Thanks!