Christmas is coming and I'm sure she will be delighted to find a new cordless vacuum under the tree!
A few years back, I bought Mrs TB a Dyson V8 cordless. She was genuinely pleased with it.
The battery has just gone a bit wank, and as (being an old model) another identical one was only just a smidgeon more than double the cost of an official battery, I've just bought her another. Being the modern man, and all that
To raywilb, I do recommend the Dyson cordless ones, with the proviso that whilst they are great "daily" cleaners (we have 2 moggies that leave fluff all over the place all the time), the "spring clean" vacuuming is done with a mains powered upright (in our case, yet another Dyson). The cost is a little silly though, unless you catch one on a decent offer.