We give everyone, one of these desks....

http://www.ikea.com/ca/en/catalog/products/S49022524/#/S5902...

We had existing desk tops so we just had someone come in and install the legs. They work well and given that we tend to average 4 27" monitors per person they handle the extra weight well. Mechanical riser's are awesome!

They also rise fairly high, important when you have someone who is 6'9" on your team:)

Just don't forget to buy a standing mat to, ummm, stand on.

http://thewirecutter.com/reviews/best-standing-desk-mat/

EDIT Yes, the mat really matters, we've had a few ergonomic experts in and their advice usually varies but they all agree on using a standing mat.