That's the Block of the Day Archive. In order to view, one has to sign up.
So without actually seeing the blocks, you can make the HST's any size you want, especially since you have such a variety of sizes anyway.
When you're done with your blocks, you're going to have to lay them out in a way that's pleasing to YOU, and then figure out how to make them fit together.
If you just want blocks in a grid format, then, yes, you could borders around the smaller blocks to make the the same size as the larger ones.
Or, you could combine smaller blocks (let's say four 5" blocks), and then but a border around the larger 7" blocks so they would all be the same size.
Or you could have a totally free form setting, where you'll just add pieces where you need them, by doing partial seams, and use every other trick in the book.
Wanda over at
http://exuberantcolor.blogspot.com/2...al-part-4.html was recently working on modular pieces - which is kinda what you have.
The link is to Part4, but if you work your way back through her blog entries, you can find the beginning.
It might give you some ideas.
You might want to pick up the book Setting Solutions by Sharyn Craig.
http://www.amazon.com/Setting-Soluti...352442&sr=8-1/
It's one of the best books I've ever read - and I do mean read. It deals with making fabulous quilts with blocks of different sizes and color collections. Worth every penny.
My bee and I did a Round Robin based on it. Best quilting experience ever.
I'm personally not a big fan of grid patterns. It's a great opportunity to come up with something very unique.