Whats a great canon lens? For portrait and landscape?

If you are building a portrait studio, a move to FX could be worthwhile. Cost is a concern, but not weight. People will pay you to make the kind of big enlargement for which the family photo nut's camera is not adequate. The Canon 5D Mark II looks like a good choice, although there is probably a Mark III model not too far around the corner. For now it could be worthwhile to invest in EF lenses rather than the EF-S lenses that would be great on your current camera but not your next one. The Canon EF 100mm f/2.8 USM macro is one that could serve you well now and in the future. While you wait for the 5D Mk III to come out, you can work on investing in your lighting equipment, which is very important to good portraits.