Hi Warthog
At the risk of contradicting Walter (yet again, but nothing new there), I absolutely adored Samarkand and wandered all over the town on my own.
Loved the fancy, tiled buildings (Registan etc) and stayed in a cheap hostel just down the road from it- private rooms with bathrooms were very reasonable and the shared dorm was fine BUT the toilet for the shared dorm was possibly the worst loo in the 'Stans, and that's saying something

However, I suspect your Mum would prefer somewhere a bit more upmarket.
bear in mind that it does get really blisteringly hot so it's better to go Spring or Autumn and try to avoid Ramadan.
Bukhara and Khiva are also definitely worth visiting and they are quite easily accessible- good roads in Uzbekistan, just watch out for the police with their speed guns.
I'm going to be back out there again in May, so I'll have a bit more info then.
contact David at Stantours- he is very knowledgeable and helpful, also take a look at his company's website for further info
STANTOURS - Central Asia Travel Resources
Good luck and I'm sure your Mum will have a fantastic time.