Can anyone recommend a good block set?  

Well there is alot of choices out there. My daughter loves blocks. She has the big lego blocks which is better for little ones who like to stick things in their mouths. She also has wooden blocks that can be found at places like walmart, target, kmart. Also you can even let him play with your plastic containers. That is what my daughter does while I am cooking. I pull out the plastic containers and lids, put them on the floor and she has a ball. Anything is find as long as it doesn't fit in a toilet paper or paper towel roll. Anything smaller would be a choking hazzard. Have fun with your little one.

We have Peek a blocks with both my kids loved and still do.
I highly recommend Melissa & Doug cardboard blocks. They are big so when he starts walking they are really easy to stack. A little big for the sitting stage.
We also have a bag of foam blocks. They are great. No need to worry about them hurting themselves with the blocks. We have wooden onesbut I know both kids ate paint chips because lets face it kids eat everything.
The foam blocks are by Imaginarium. Highly highly recommend them!