Koolio- Thompsons is a thinner product that will soak into the wood, it will protect it but I don't think it will give you a slick washable surface like a polyurethane will. (Someone correct me if you don't agree) I've use a product from Lowes and just got something a little different from Sherwin Williams. SW has 50% off sales sometimes making their stuff cheaper than Lowes.
It will tint the wood but it's not a bad look just sort of a golden hue?? If you are going to do your stalls and tack room I bet you'll need at least 5 gallons. See what you can get that comes in a 5 gal bucket because it will save you some money. But If your going to go to the work of doing it I wouldn't go with anything to cheap because that would defeat the whole purpose
And I would suggest doing it ASAP!!!!That's what I'm doing right now with my stalls and It is so much work!!! We built our stalls in stages over the last two years so some of them I was able to do as they were built but some were built during the cold of the winter and so now I'm having to go back and try to clean them. It's a pain in the butt!!! Not just the dirt but the fly mess is ridiculous.
I'll post some pictures in a bit so you can see our wood before and after, that might help you decide.
Another decision is what finish you want, I think poly comes in satin or ......can think of it, something shiner LOL which is what I went with.