At that age, you can let your son cry it out with out worrying about any effects. We had a similar issue with my son, except he started not even going to sleep, he'd sit there for 2 hourse and stay awake, just to make sure I was there and after trying everything else, crying it out was the last resort and the only thing we could do. First night was the hardest, second night was better and by the 3rd or 4th night he didn't wake up anymore. And if he did, he put himself back to sleep with out crying.
The only suggestions, I'd try before the cry it out is...do yo have a night light in the room (if not maybe he's scared of the dark alone) and/or how about a noise maker. We bought a $20 sound machine, we turn it to the waterfall mode and it's just like white noise. If some noise is waking him up, maybe that'll drown the noise out and he won't wake up.
Otherwise, it sounds like your son wants a playmate in the middle of the night, or just want's to say hi to mommy like mine did. We did the full cold turkey cry it out where we didn't go in at all. First night I think he cried for a over an hour, second night it was 45 minutes, after that 20 then nothing. I know as a mother it sounds harsh to let your child cry, but as I said we tried EVERYTHING else and this is the only thing that worked for us. Occasionally he wakes up now, but not every night and not every week either. And I have noticed absolutely no differences in how my son acts toward us. He's still the loving happy go lucky, ham-it-up little boy he was when I'd go in and try to get him down.