Since I can’t tell if this is interior or exterior, I’ll give you info for both.

First things first, do NOT use any Thompson’s Wood Seal. It’s the absolute worst thing on the market and a HUGE pain to remove once it’s been put down. Even after it looks like it’s been gone for months, there’s still a wax residue left behind that MUST be removed before putting anything else down. Thompson’s is a siliconized parafin. It isn’t affective all that long and is a pain to fully remove so you can apply something else.

For Exterior:

Pigments are your friend. They are going to give you the UV protection from sun damage and oxidation. Wood outside turns gray as it oxidizes. It’s a natural process and ALL wood does this eventually. If you use a semi-transparent exterior wood stain similar in color to the natural raw wood color, that’s your best bet. Don’t worry so much about making the water bead up on the wood. It’s much more important to protect the wood from the sun damage than it is to protect it from water. Exterior products contain mildewcides and fungicides to protect against all the nasty things that happen with water.

Do NOT use solid color stains on your exterior wood. They are essentially thinned down paints and are not real durable. They also need more maintanence than transparent or semi-transparent stains.

Before applying any stains, your wood needs to be properly prepared. It doesn’t require sanding all of it, but I’d definitely recomend using a wood cleaner, a scrub brush, and a low PSI power washer, (1000 psi-1500 psi…max), to clean it all. You can apply the wood cleaner with a regular exterior canister sprayer. You usually let it sit for 15-20 minutes and then aggitate it with a scrub brush. Then power wash it off. After this, you’ll need to let it dry VERY well for several days of warm, dry weather. Then you’ll be ready to apply your exterior stain. I personally like to use Cabot products. http://www.cabotstains.com/shared_frames.cfm?area=towoca&cabot=1

For Interiors:

If you’d like your natural wood to look nice, you can seal it with several different products. Lacquers dry fast, can be sanded easily between coats, and area fairly easy to work with. The downside to lacquers is that they tend to "blush", (looks like someone spread talcum powder on the surface), when they come into contact with moisture. Lacquers are not appropriate for areas with high humidity of heavy use. They’re not overly durable, either.

Danish wood finishes are nice, but give very little protection to the wood. They’re esentially a stain with a little wax to give a soft-buffed look. Beautiful, but not real practical on wall. Especially in a heavy traffic area.

Polyurethanes are extremely durable, but the solvent based ones yellow in areas of low light. (Areas with more light don’t yellow nearly as much.) Water based polurethanes are easy to work with, but are a little less durable than the solvent based ones. But both products are some of the most durable on the market for interior wood. If you like that natural, buffed wood look, get them in a satin finish. It’s enough sheen to give you some protection but not enough that it will blind you looking at it.

Varnishes are usually solvent based, but there are some out on the market that are water based. They’re usually a minimum of a semi-gloss sheen and show every little ding or imperfection in the wood. They’re durable as hell, but not very pretty on anything other than trim pieces.

is the wood dry? you might want to check the moisture content of the wood before applying a stain. But once that is confirmed, I would go with a Watco natural stain, if its going to be outdoors then something made by Thompsons.