Dear Larry: I would suggest a five quarter oak tongue and groove floor would go nicely, and provide great strength. One way to save money would be to buy your own small saw-mill, there are some nice band-saw model, and the cost of oak logs is much less per thousand, than those boards found at home centers. In order to complete the project, you will need log handling vehicles and equipment to handle the logs. Once the boards are sawn and properly air dried, you will need a planer to take off the rough and to size the lumber more precisely. Now that you have all of this lovely equipment, you may want to saw a few house patterns for your buddies. I would be willing to bet that they would throw you one heck of a beer bust if you sawed a pattern for them, and you would have friends for life. By the way, those slabs and the pile of saw dust are recyclable items. If you have intolerant neighbors, you may want to consider methods of abating the noise of sawing, but neighbors who live a mile or more away, should have no problem, even without noise abatement measures. You may want to call on a specialty shop to have the tongue and groove edges applied, unless you want to go right ahead and buy a commercial grade router with bits sized and shaped to do the job. You may think these suggestions are a bit over the top, but have you ever walked across a solid oak floor with the above thickness. No bouncing and it will last a lifetime.
Yours Truly, Clifford Wilson [Non-text portions of this message have been removed]