Thanks.

I, like most, probably have the following options:

1. Book via hotels.com, pay with credit card at the time of booking in GBP but of course based on local cost and currency conversion.

2. Book via hotels.com, reserving a rate based in local currency, pay by credit card when I check out.

3. Book via hotels.com, reserving a rate based in local currency, pay by cash when I check out.

If paying at check out is only of marginal benefit I would probably just pay in advance as it's less hassle. But if there's a good benefit to me and/or the local hotels I'm happy to do whatever.