In reply to EuanM:
Euan,
Really depends which part of the Dolomites you are in.
From memory, there is a pleasant route out of Sest/Sexten on the north side of the valley which basically follows the border with Austria. It has a few optional cut off points whihc return to the valley at various points.
Heading out from the same town, there is a trial which leads out in the other direction, gaining a bit of height and bringing you out at Tre Cime. Stunning views. Again from memory, this can be turned into a circular route around (I think Monte Paterno??) to return to the valley.
Further afield, the circuit around Lago Di Braies is stunning and can be extended up to one of several rifugios. The car park near the hotel gets quite busy at weekends, but the views make up for it. Not so much height gain initially and it is quite gradual when you are away from the lake.
There are also some good options on the Plateau at Compatsch, or up and onto Scilliar/Schlern. And the circuit around the Plattkofel and the Langkofel is generally really good trail with a little height gain. The heigh gain is increased on that circuit if you go up to the Rifugio between the two mountains. This is also handy for a refreshment stop. You can pick this route up from near the Sella Pass.
I hope this assists? Am travelling to Chamonix just now, so typing this in the car purely from memory.
Kev