As a wood scientist by trade and education, here is my professional opinion....
Thompson's is a waste of money...all it is is a wax emulsion that will last a few weeks. The wax will 'float' off sooner or later. It ony sits on top of the wood, with little adhesion.
Next best is a oil based paint or stain or poly. This group includes paints, stains, varnishes, urethanes etc. This does not seal the wood totally, but does a MUCH better job than Thompson's. Has some adhesion but, again, it sits on top of the wood.
A better alternative that the oil based is a vinylester resin used for fiberglass. This will penetrate the wood and encapsulate as well. Three coats is gonna last a LONG time. Make sure to do all edges, sides and penetrations (SCREW HOLES). Basically anywhere water could possibly get. There are many, many million dollar sportfishing boats that use this philosophy that are DECADES old with no rot.
The best sealant IMHO is an epoxy fiberglass resin, used the same way. A little upgrade in technology and durability as well.
Another thing to consider is that using the oil based systems, any carpet put down over them is adhering to the finish and not the wood. Concievably, one mav be able to pull up the carpet and have finish clinging to it instead of the wood. Not a good situation.
Just my $0.02