I grabbed a pair of the base layer pants last fall... put a lot of miles on them biking, and a lot of days wearing them. They show no wear from all winter... and recently pulled them back out of the closet for further testing. Coolest I've ridden in them was 25 degrees...

Wednesday's night ride... 2 hours, at 38 degrees. Wore them under a pair of jeans. Never once was I to hot, or to cold. Best thing... Not sweaty!

As a top I had a thin zip up jersey and a t-shirt, plus a base layer by a bike specific manufacturer, equivelant of a wool sweater, just a little less aerodynamic drag, and a little more wind resistant.

Expensive! But I'd say they are well worth investigating. Flat out puts to shame wool long johns, cotton long johns... and the scratchy polyester cheapos.

Capilene is great for activities like biking and hiking. For travel? Not so much. They wick great, but they stink. I love my silkweight for summer time activities. I actually think they keep me cooler than if I would go without a shirt, plus they keep the sun off ya.

Icebreakers, merino wool apparel out of New Zealand, is also worth a look. Believe it or not it is actually pricier than Capilene but has the distinct advantage of not smelling. Don't let "Wool" scare you. This is awesome stuff if you can afford it. In a sense merino wool is nature's capilene.

I'm wearing an Icebreaker t-shirt right now... I don't think it's been washed in months and it doesn't smell at all.

As am I - a bodyfit 260 short-sleeved t-shirt. It's perfect for travel, especially if you don't know quite how warm/cold it's going to be as it's pretty versatile that way. Just come back from Copenhagen (colder) to Edinburgh (not so cold) and it's ideal. It's also a great hiking base layer. It's expensive, but you get what you pay for in this case.

I agree, I bought a pair of the patagonia capilene unders and though they are comfortable and warm, they dont last as long without a wash. Going to try some woolies.