I started looking at 55 gallon tanks. The only difference between 55 gallon tanks and 75 gallon tanks is depth. The 55 gallon tank did not seem deep enough to me. As such, I started looking at 75 gallon tanks. Since I was going to be doing a lot of the work myself, I did not look at package deals too much. I finally found an All-Glass Aquarium on sale for a little over $100. Since most of the 75 gallon tanks in my area were about $150, I jumped at the lower price. The fact that I was buying from a reef-centric fish store made it all the better.
I went ahead and got two holes drilled in the tank. The holes are visible in the picture above. They are in the back corners of the tank, and are 1.5" in diameter. I chose this size to run two .75 inch bulkheads (purchased from MarineDepot.com I figured two bulkheads would allow me more flexibility in where the overflow water went. One could send water to a refugium, and one could send water to the sump.
Note that most 75 gallon tanks (at least) have tempered glass bottoms. This means that they are stronger, but that they cannot be drilled.
Some people drill holes in their own tanks. Having read up on it (and pricing it), I decided that it would be easier to have a glass shop do it. The bits to drill the holes (diamond-tipped) cost more than what the glass shop charged me. In addition, it really takes a steady hand and nerves of steel to drill glass.