I have the Rapha trousers and they are actually very nice for my short commute (~6 mi each way max). They feel much nicer and wear much better than my Levi's jeans that they replaced (for riding bikes at least). For example, they do not show appreciable wear after months of regular use, whereas the jeans developed holes at rub points after only a couple of short months. The Rapha fabric is slightly stretchy and drapes very well. It also breathes surprisingly well without being too airy for winter (OK, so it's CA "winter") so my legs don't get uncomfortably sweaty after impromptu "Cat 6 races".

I got them for about half off retail during one of the occasional Rapha sales, so you may want to wait a bit for those. If you do order, be sure to order your true size (i.e., not vanity size) and you may need to trim to length as they only come in long. I'll advise to stay away from the black version as that picks up lint like mad.

Another brand you may want to consider is Betabrand. I've not tried them yet but they look interesting, the price is better and they're made locally here in San Francisco.