The Terrace Level is located on the third deck at Yankee Stadium. Surrounding the Jim Beam Suites are Terrace Infield seats. These seats have a great view of the scoreboard in center field, but are much higher up than 200 level seating.
Because of the intimacy of these sections (fewer than ten rows per section), these are a great option for quickly getting in and out of your seats. However, with up to 25 seats in a row, you'll want to get aisle seats to avoid having to step over a dozen strangers to get in and out.
From a shade standpoint, these seats are not very well covered. Sections 313-316 will be your best chance to be in the shade first
One final issue with these seats is the Standing Room Only crowd located behind them. They make for more crowded lines and concourses and may occasionally try to poach your seat while you're away.