I have two tripods. The first is the Manfrotto 055CXPRO3 + RRS BH-55 ball head. It's moderately heavy and fairly large in size. It is transportable, but it will only fit in a check in suitcase. On your back, it is hard to fit it comfortably on a camera backpack. Hence, I generally carry it in my hand or I mount my camera on it and walk around with it slinged over my shoulder. It is very steady.
The second tripod is the Gitzo GT1542T + Markins Q3T ball head. This tripod is small, very light, and fairly solid. It will pack in a backpack, and is much easier to transport. The ball head is great. I just went to the zoo with my 60D and 70-200 f/2.8 and it worked great.
Since you want to shoot for landscape and portrait, you may want to consider an L-bracket. Both of my tripod heads will allow me to flip the camera down to portrait mode through notches in the heads. Both have panning bases which allow me to adjust the camera positioning. In comparison, the L-bracket permits you to take the camera off the head, flip it, and lock it in without having to adjust your tripod or head at all. My L-bracket is made by RRS, but other vendors make them too.
One last tip is to look out for deals. I got my Gitzo "used" on Amazon for 1/2 price. I think it was purchased by someone who put grease on the middle section threads. Amazon could not resell the unit as "new" so they sold it as used. It appears to be near brand new. I got a steal.