Hmmmm... I love Bostons! I am not sure if a boston would do well being home alone for a long time. A Pug would do fine... if you were talking about my pug. Have you ever thought about getting 2 dogs so one dog has a playmate?
Or the other way around.

If you want a medium sized dog, I am not sure. I was thinking about Beagles, boxers, Austrailian Shepherds... But all of those breeds need a lot a attention and care. All dogs do of course, but these breeds can be known to need a lot of exercise.

If I was in your case, I would definatly get a MIXED BREED. They are just wonderful dogs!
I found a dog at my local Humane Sociaty, and she is so adorable. I fell in love with her when I first saw her. Her name is Clara Belle, but I call her Belle for short when I go to see her. She is a mixed breed, but again she loves to run and she would need a lot of exercise. She got at the Humane Society because she chased cattle. Oh I wish I could get her. I will post a pic if you want... she dosen't have a very good pic online so you can see the size of her... O.k. i need to just shuddup now. I always just get up in a roar about talking about her...

GOOD LUCK!!!!!!!