You might benefit from teaching him to play by himself. My child does this wonderfully, and I worked on it with her from a very early age. Some suggestions I read in a parenting magazine:
Start your child on an activity, tell him you’re leaving but will be right back (my daughter still perks up at those words), and come right back. Then work the “right back” into longer and longer intervals. This both reassures him that you really are coming back and that he can play on his own.
Also, vary the activities and the intervals so that he gets more and more comfortable with being alone in a room and entertaining himself.
One thing I did that does require space in your home: I made a true kid play area. We have a semi-finished basement that is great for this. My sister ran out of space for all of her toys in her house, which is about 1/2 the size of mine but much nicer and newer, so I told her I’d hold on to them if she didn’t mind them being used. So we put a bunch of toys that I’d gotten at a garage sale and that her kids didn’t play with as much down in our rec room. I have gotten more kid-use out of that room than out of any other in my house. I just walk my daughter down (the handrail on the stairs is not the best), tell her I’m going upstairs (she immediately smiles, waves, and says “bye bye bye bye…”, she plays for a good while, and I get to clean or whatever I need to do. It’s been great when others come over too. My sisters and I all have girls, and a friend has a boy about my daughter’s age. Because I’m pretty gender-neutral in the toys I buy for my daughter (I was a tomboy, never really into dolls) he was happy there for hours!
Other things to think about: I know that attachment parenting advocates are often against schedules, but I’ve found that my daughter is much less needy and much more focused when we have a routine. We usually get up around the same time, and have the same basic routine week by week. As she gets older it seems to be less important that the daily routine be the same. Also, I make sure to get my workout and shower in while she’s at the Y’s nursery, which both lets her play with other kids and different toys (they even have Totsercise!) and gets me the long, hot shower that I love.
Anyway, just some thoughts. I hope they help and that I haven’t gone on too long.