My comments are generally in line with others:
Clarks is expensive, and the fact that they don't publish their price list (even on site) is super annoying.
BUT, they have really, really nice wood, and a very wide selection of species and widths/thicknesses, and a lot of it available quartersawn. Most of the employees are very nice.
Houston Hardwoods is cheaper, but the employees are very gruff and don't want to give you much of their time. Their selection is much smaller (species, but especially widths/thicknesses).
Both will allow you to pick through the bins as much as you want. Clark's is much quicker to help you with crosscuts to fit stuff in your vehicle, if needed.
I find myself going to Clarks now (I used to go to Houston Hardwoods) because I invest way more valuable time in my hand-tool-oriented projects for myself and my family than I do in dollars into the wood. If I was trying to do this commercially, I might try to get cheaper wood.
The higher quality wood (all heartwood, no knots, no cracks) does save some money from reduced wastage, around the edges.
Finally, we should count ourselves as lucky to have quality suppliers, and I want to reward Clarks for having what I need and relatively good service, despite the higher price. It's also much closer to downtown, so that has an impact.