Many people take more than 2000 IU vitamin D3 daily but they won't have the same health benefits as someone has from careful sun exposure.
http://ajcn.nutrition.org/content/105/5/1031.full
That's interesting. Another good reason to get outside.
I take 4000 per day. I was at 2000 and was on the low side. Doc said up it. I have never heard of anyone who is on the high side or even above the 1/2 mark on Vit D. Seems like everyone is low - maybe if you work outside a lot or run everyday, but the other set of doctors say use lots of sunscreen.