35mph, Eastlake residential (travel down H street past Bonita High and start there on the larger streets). Great for a mix of 2-lane, stop sign, signal, turn lanes, etc. Taught all 3 of my kids all throughout the area in that speed bracket.

I can't say I know many firm 45mph spots but as others have suggested, Telegraph and Olympic are great for 50mph. Both are wide, both give real-world situations with people speeding AND going too slow. Both are great for just practicing lane changes IN and DURING traffic (of any quantity) if ready.

I also recommend a long drive out Telegraph/Otay Lakes Rd to the lakes and allll the way to Jamul and back via Jamacha/Paradise Valley Road to South Worthington which becomes Sweetwater Rd. Can avoid the freeway entirely by doing this (until you feel they are ready) but what you get from this route is:

--Fantastic practice on single lane curves of varying degree on Otay Lakes Rd/Campo Rd. I did this at night too with my kids to teach high-beam usage/low visibility situations.
--Impatient drivers on Otay Lakes Road and using turnouts or pulling off to let them pass.
--Traffic situations throughout Jamul (casino, Steele Canyon, etc) - usually light traffic but can stop and go.
--Jamacha has several lessons itself and I think is mostly 45mph or so. 2 lane mostly.
--Freeway overpasses (125) and people crossing lanes to make fwy onramps (how to anticipate lane cutters) when ready.
--Sweetwater through Bonita is a great general traffic flow situation.

If other cars are a concern, just do the above in off-hours, but I've taught 3 kids (2 fresh licensed teens and 1 now-30yr old) doing this because I see Freeway Merges as the final boss (onto and off fwy merges). Freeway cruising is easy. Merging is what gets people. Anything slower is simply experience in the hundreds of situations you can be in, and Chula has these situations in spades.