Skanska USA and architects Pickard Chilton bring their plans for a 34-story retail & office tower before the design review board tomorrow night. When they do, they'll be presenting two very different designs for their development called 2&U, which will rise between First and Second avenues and Seneca and University streets. The first plan calls for 690K square feet of office space, 30K square feet of retail space and 500 stalls of underground parking. The 1890 Diller Building next door at First and University would remains standing but this version calls for the dreaded "alley vacation" from the Seattle City Council. The second plan would have the 34-story building take up only the eastern half of the block, leaving the other half open for future development. This choice would have 510K square feet of office, 12K square feet of retail and 400 underground parking stalls. Whichever way they go, the eventual building will have to focus on the eastern side of the block where zoning allows for 450 feet, which the western half does not.