Well, I've been waiting to read the rest of the post, but in the meantime, here are suggestions:
1) 'Zephirine Drouhin' is what most people think of when "thornless" is requested. It also has two sports -- 'Kathleen Harrop' and 'Martha' -- so you could get a mix, or multiples of one. These are repeat-blooming.
2) 'Lykkefund' -- it's thought to be an offspring of 'Zephirine Drouhin', the other parent being Rosa helenae. This is once-blooming, but if you want to get creative, you could put clematis in there. I'd suggest choosing a clematis that can be hard-pruned in late Winter when you're pruning and training the roses, then let the clematis grow as it wishes into the roses.
3) Any of the Boursaults you can find. Look for 'Amadis', 'Blush Boursault', 'L'Heritierana', 'Mme Sancy de Parabère', or 'Morlettii'. I think this is all that's commercially available, if that. You'll probably have better luck finding them in the UK than we would here in the US.
4) I don't know if your climate would support them, but another possibility would be a Lady Banks rose. There are four forms available -- single white, double white, single yellow, and double yellow.
:-)
~Christopher
