The only rest area I can remember is just north of Ann Arbor. To stay on 23 is a left ramp so if you stop at the rest area, when you leave the rest area get over in the left lane. It's about 5 miles to the left hand ramp to stay on 23. THEN you need to get into the righthand lanes to go south on 23. I do believe 2 lanes go right to stay on 23.
23 does not connect directly to 90. You have to stay on 475 and go east and pick up 75 that does connect to 90....OR...get off at exit 6 and take the surface (off highway) road to RT 20 and turn left (again, get in the right hand lane after you turn left onto 20 for the on ramp to 90) and that is the closest on ramp to 90. I take this route when I need to get on the turnpike. Been this way countless times because I used to live in Davison MI and also Cleveland. I hope I made sense to you.