Thinking of spending two nights here sometime in the last two weeks of May. RS guidebook mentions some lifts and hotels are closed in May. Is this a bad time to visit?
Some may, but the ski area on the glacier at Klein Matterhorn is open year round. May is between seasons. The primary ski season ends in April and the hiking season does not get going until late June, so that is a good time for repairs and vacations for the locals, but it won't shut down completely.
I'm primarily going for hiking (Matterhorn views) and not necessarily for skiing or going up any mountains (at least not Klein Matterhorn). Should I nix the idea of going? I worry if I book too far in advance I might get bad weather when I show up, but I know this is hard to predict.
Well you do get some very nice uncluttered views of the Matterhorn when you get up out of the valley, especially the Gornergrat for the classic profile. Trockner Steg, on the way to Klein Mattterhorn, is particularly good view of the East Face. Seems like you could reach out and touch it.
Without riding a lift, hike up to Restaurant Ried for a good view. It is fairly gentle uphill hike on a rustic road (Riedweg).
As you mentioned, all is for naught if the weather is lousy.
Late May is an excellent time to visit the alps. Some high elevation trails and lifts will still be closed, but there will be an abundance of other trails available. Crowds are not as thick as in the summer and the spring flowers are crisp and beautiful. It's my favorite time to go.