Stayed at the Residence Inn Tustin (15181 Newport Avenue) over a long weekend in April. Very convenient for Irvine and Costa Mesa. I couldn't find any comments beyond this old thread, so I'll add some here.

Had a studio king on the second floor, later moved to the fourth floor. Both rooms in very good, even great, condition. The TV rotates smoothly to face any part of the room, and it was easy to use with a USB streaming device. Less good: both rooms (odd numbered) faced the 55, which sounds like a racetrack 24/7. The roadway noise was so aggressive that I kept checking if the windows were fully closed. Running the a/c to get pink noise was somewhat beneficial.

Breakfast was pretty sad. No fresh hot food at all ... just some tacos, waffles, and cheese/meat bagels kept warm in their plastic wrapping under the heat lamps. Also, some oatmeal, cereals, breads, sodas.

Every staff member (and they seemed well staffed) was friendly and helpful. Overall, the facilities, location, and competitive price made it a good choice.