All the medical and anecdotal evidence points to 12h, 36h, 60h, etc. as being the best compromises for downroute rest periods. Unfortunately (and I do have some sympathy with the airlines here), unless you have more than one flight a day to a particular destination, it is likely that it is scheduled at the same time throughout the week, thus generating 24h, 48h, etc. slips. Not really anyone's fault and hard to see a solution.
In terms of ULR, I used to think that it would be easy to cope with minimum rest and get more days at home but having done it for over a decade now, I would be loath to give up the part of our agreement which gives us a day off downroute before/after an ULR sector. I find it gives me the chance to get out of the hotel, do some exercise, enjoy some decent food & drink and get some quality sleep as a result; this leaves me able to get on with my life once I do get home, rather than wandering around in a stupor for a day or two.
We do have "rest facilities" but they're not the greatest and being a light sleeper I find it difficult to get more than 3-4hrs interrupted dozing out of a possible six-plus on a 14hr+ sector, so having had a good kip before is important for me.
Another issue is the length of duty with ULR. By the time you add in getting to and from work you can be up for >20hrs at a time, which is not something I would recommend doing repeatedly over a short period. I don't think you really fully recover and end up slowly ratcheting down without realising.