I have 3 accounts:
1.) Main GMail account. Used for my Android phone and all my personal and work emails.
2.) Yahoo! account. It was my first email account but I rarely send emails from it. Most emails in this account are from companies like Apple and HP sending me information about their newest "deals."
3.) Craigslist account. I hate using my personal account when it comes to Craigslist, and I don't like fishing for emails from potential buyers through all my other emails, so I now use this exclusively for CL.
I have no problem managing all 3, and it keeps my emails organized.