Having returned yesterday, thought I'd report on suggestions here:
Skywalk was good. Knowing what to expect helped, $300 for 4 was pricey but not unexpected, so liveable with. Having done the South Rim before, the West was different, but still extremely impressive. The Skywalk itself was good - I have no problem with heights, but I think a couple of the guys I was with found it fairly exhilarating! Bought one group photo ($30), and will scan/share between the 4 of us. Was about 3 hours from Vegas, including about 9 miles of unavoidable dirt road, but no problem. Car got fairly dusty, glad we swerved the convertible in favour of yank-tank SUV in the end. Did the dam/bridge on the way back; day worked out really well.
Didn't do Riviera steakhouse, sorry Simon, but did do the Steakhouse at Circus Circus, which thoroughly deserves it's reputation. It was very very good indeed. Nice ambience, great service, superb food. Went down very well indeed. <$100 each although only had 1 bottle of wine
Other main meals:
Outback steakhouse - chain restaurant, but very very nice steaks
Hooters - chicken, shrimp and cheap beer. Yum yum
Buffet at Fremont Hotel (Downtown) - old school Vegas buffet, $15 prime rib dinner. Was on a recommended list, and for that price it was excellent. Good selection. I only had 4 main courses (prime rib, sushi, pizza, mexican), plus salad and dessert

.
So a good mix.
One thing we learned is that if you're not gambling, the price of drinks can vary massively. From paying nearly $40 for a round of beers in the Venetian, we found we
could get $1 bottles or frozen margaritas just down the road in Casino Royale (even not gambling)
I loved this place (and the bar), has a downtown feel to it slap bang in the middle of the strip!