I want to have as many features of a good 8x32.
Docter Compact 8×21
Opticron DBA Oasis 8x21
Nikon HG L 8x20 DCF
or.....
The problem with wanting a bino in the 20-21mm class is that you will not have any features of a "good" 8x32. While choosing a 20mm will get you a decrease in weight/bulk (which seems to be your major concern), you also give up field of view (FOV), brightness, and for the most part resolution as well. Yes, you can find a few such as the Opticron DBA that will get you very good FOV, but now you have increased weight by about 50% over other good 20mm binos.
If you don't mind carrying around 12 ounces or thereabouts, then besides the excellent Opticron suggestion above, you could also look at the Bushnell Elite 7x26 Custom Compact, and the Swarovski CL Pocket 8x25. Might as well go with a larger objective lens if you are going to carry that much weight. The CL Pocket comes the closest to a 30mm bino of any 20 or 25mm bino that I've ever seen. The Custom Compact has a very bright view, brighter even than the CL Pocket. The CC however is not waterproof, so this might be a concern for you.
If low weight is of concern, then you should consider the binos in the 8 ounce area. A good one that is rather low in price is the Alpen Wings ED 8x20, which weighs about 8 ounces. These are very sharp in view, and in fact are as bright as any other 20mm roof in or near it's price range. It is even sharper and brighter than a 8x20 Zeiss Design Select that I used to own. It's eyecups snap into place very well, and stay put. These are the best 20mm binos I've seen so far in the $150 price range.
Otherwise, if you want the highest quality view in a small and lightweight 20mm-class bino, then you will need to go with the Nikon, or the 8x20 Leica Ultravid HD, or the 8x20 Zeiss Victory. Any of these will do just fine. In this case I prefer the Leica over the Zeiss. I haven't used the Nikon, but I have a feeling that it will provide more optical goodness for the dollar/pound/euro spent than the other two.
Lastly, there is also the Hawke 8x25mm Sapphire, which I believe only weighs about 9oz.. I've not used one, but the reviews seem to be quite good. It's price sits right in between the Alpen and the Nikon. These might well be best combination of price vs. quality in a bino that meets your need for a compact travel binocular.....