For two man operation the LAR series Auto (Dumpy) levels are a good choice. These can be supplied as units on their own or as a kit complete with the tripod and the staff. The staff comes with a clip on levelling bubble.
For a one man operation the rotating lasers would be a good choice. The 66R is the easiest to use. Just set the height and trn it on. The unit will self level and you simply use the laser detector to check your levels.