Even if you avoid the Autopilot, you can still use the Traffic-Aware Cruise Control, which buys you braking and accelerating when approaching the other vehicles, but does not do lane changes / lane assist for you.
TACC reads and interprets the speed limit signs. From Model 3 Owner's Manual:
"Traffic-Aware Cruise Control makes it easy to cruise at the speed limit. You can cruise at the speed limit that is currently being determined by Speed Assist (see Speed Assist on page 78). To do so, move the gear lever fully down once then release.
When you release, your cruising speed is set to the speed that is determined by Speed Assist, taking into consideration any offset you have specified. If you are already driving faster than the speed limit when you pull the lever, the set speed does not adjust to the speed limit—it adjusts to your current driving speed."
With TACC enabled the only time you have to keep track of speedometer is sign edge cases (e.g. Limit 25 but only when children present) or if the speed limit was obstructed.