Best base layer on top..jeans on bottom.

I prefer wool as a base layer, for cold OR heat. It doesn't get clammy and stick to me the way other fabrics do, nor does it get as smelly.

Socks: I prefer Smartwool, but there are other brands.

T-shirts: I like the Ibex short sleeved t-shirts, again for hot or cold weather. They could be part of your regular wardrobe, too, so it won't be something special you're packing just for this part of the trip.

Heavier base layer: I have heavier Smartwool long underwear, bottoms and long-sleeved tops.

Another option: I also have Smartwool camisoles.

So perhaps something like that would work? Of course it's impossible to predict the weather, and everybody has a different temperature tolerance. Hope you find something that works for you, and have a good trip.

I use Craft base layers for cross country skiing, including skiing during blue ski 50F days. Craft's website selection guide includes recommendations based on activity and temperature:
http://shop.craftsports.us/baselayer-guide
Variables include temperature, activity, intensity, sex.

Craft base layers range from keeping cool to keeping warm and dry:
http://shop.craftsports.us/performance-baselayers

Craft’s functional baselayer is designed to be worn next to the skin.
The structure of the fabrics and the stitching techniques interact to
effectively transport moisture away from the skin and distribute it on
the outside, where it either evaporates or is passed on to the next
layer. For optimal performance and comfort, Craft’s baselayer should
always be worn underneath your outer layers, regardless of weather
conditions.

Our range of functional baselayer consists of three categories - STAY
COOL, BE ACTIVE and KEEP WARM - complementing each other. With three
categories, we offer a baselayer range with unique performance
characteristics for intense physical activities in all conditions.
Consult the graph to see which category works best for what
conditions.

Jeans never dry.

Merino wool for a base layer...yes, including that which covers private parts. I add a merino wool zip-t sweater as well. Jeans? Forgetaboutit!

I wear Icebreaker for years. They make from merino wool, good for both cold and hot weathers. They are not only keeping you warm as base layers but also preventing clamminess and resisting odor for days.

I am going to Switzerland in May this year and they are the clothing I will take with me.
Here is the link, they are quite expensive but will last you a long time with proper care.

http://www.icebreaker.com/en/home

Thanks for the great tips.... I have gone online and looked at icebreakers and they have a sale going now. What does anyone recommend as far as short sleeve or long sleeve for Switzerland (Murren) in early August? I am thinking maybe short sleeve and layer .. we were in Switzerland in early October 2014 and hiked North face and it was a wonder 70 degrees..it was cold starting out but as we hiked down it was a picture perfect day. Thinking now of light weight travel pants from EB I already have for bottoms instead of my jeans.
I went for a four mile hike today, on Cape Cod Bay it was cold 34 and windy on the beach I overheated and then got cold from being sweaty.. I just can't seem to get my layering right. I am determined to get it right before we go to Switzerland.
Thanks for your input.
Sue

Hi Sue, we did the Best of Switzerland tour in September 2016 (great tour!). I took jeans (I washed them in the sink, rolled them in a towel, and they were completely dry in 24 hours), Dockers (dried in 12-24 hours), and Eddie Bauer travel pants (dried in 6 hours). I'm usually warm so I took short sleeved T-shirts, a fleece, and a cardigan. I layered everything under a rain jacket. I was completely comfortable on the Schilthorn. Be sure to do the Thrill Walk in Birg (very cool!). Hope you enjoy the tour as much as we did.

I always take a couple of short-sleeve tees to Switzerland, whether June, July, or August. If it turns cold just pull on another layer.

Good places to get Icebreaker and Smartwool at a discount are Sierra Trading Post and backcountry.com. The latter also has Ibex.

I have some of each and they are different. Icebreaker seems to use a finer wool in a tight knit with a harder hand, which makes it very smooth as well as soft. The Tech Lite line is my favorite for short sleeve tees. The knit is thin but not sheer.

Smartwool seems to use a slightly looser knit as well as a looser twist to the yarn, which makes it a bit fluffier in feel. I like it for a mid-weight layer if I want something slightly warmer. Smartwool sizes seem to vary---I have tried XS that was still too big, and other XS that were too small. Just never know until I try.

Ibex also makes a nice thin knit, smooth and similar to Icebreaker. Their fit is more "shaped" than the other two, so good if you are curvy. They seem to run a bit larger than the other two.

You can also often find some of these brands on Amazon.

Check out Uniqlo heat tech tshirts and pant liners. I used them in Patagonia last yr. i was warm but never sweaty. It wicks very well.

Another benefit to wool...the stink factor is much less versus plastic alternatives.

Jeans/cotton? Don't sweat it. (Sorry, couldn't help being punny).

You appear to be going on a supported tour during the summer. Wearing jeans or cotton garments isn't going to be a life hazard or risk. You are not doing a Haute Route ski tour in the middle of winter or even a Mount Rosa circumnavigation where you can be a half day or more from shelter. In terms of risk, the end of July is summer and it's unlikely that a RS tour will have you in exposed places not near shelter or evacuation where you can dry off without fear of hypothermia.

If you are worried about over heating, take off your jacket. One option of layering is to take off a layer (or two).

I like synthetics. I want the material to look good, be light, breathable, wick away sweat, easy to wash, quick to dry, packable, durable and wrinkle-free and inexpensive. I like those stretchy dry-fit shirts in long or short sleeve as my underlayer. One or maybe two layers of fleece pullover or zippered jacket as my mid layers. And a Gore-tex or similar breathable-waterproof shell, preferably with under-arm zips for heat venting. And a toque for my head. Layered up, i can go skiing in -20 C with heavy wind chill. I can peel off layers and easily carry if hiking in warmer weather.

I still use a fleece jacket which is 30 years old. I have never had any odor problems. The beauty of fleece is that i can immerse it in water, wring it out and wear it right away while still damp and still be reasonably warm. If i hang it up, it will fully dry in a few hours. I would not recommend the thickest 300 weight polar fleece. It is too warm unless you plan to just sit in one place for a long time in freezing temps. The mid weight 200 works best for me.

Convertible polyester pants would be good. If you ar hot, unzip the legs. If you are cold or getting too much sun, zip them back on. Also easy to wash, fast to dry and need no ironing.

All of the above can be expensive, if you buy the brand names, Columbia, Nike, REI, MEC etc. Or you can get similar stuff at Costco for a fraction of the cost.

PS. I bought a merino wool blend long sleeved undershirt from Costco. 11% merino wool, 84% polyester and 5% spandex. It is nice but not really different from my full synthetic, maybe a little less "shiny".

I have tried synthetics, silk, and merino wool and find I like the merino the best - it is breathable, never gets stinky, and packs down almost as small as the silk. As someone mentioned, Sierra Trading Post is a good source for Smartwool, Icebreaker, and sometimes Ibex. Last early fall/late summer, STP had a ton of Ibex.