Ha... like Seedless says, those aren't going to be big enough, lol. Man I would die with all that room. Fucking awesome bro. Sounds like a good plan 6x6 and 5x6. I am thinking of making a larger space as well. One thing I thought of is a place to dry stuff as well. If you are going to be pulling a couple/few pounds per harvest you will need a place to hang all that stuff. You could use the veg space... just budget where when constructing.
And like SS said as well read up a lot. Find out exactly what you would like to do, and plan from there. I've probably 'wasted' $2,000-3,000 changing my setup over and over. It's cool because I found what I liked... but I would like to have that money back as well.
No matter what I'm sure you'll do alright. You're starting off on the right foot hanging with the crew we got here (if I do say so myself, haha).