For me I have these magic numbers I go by on the speedo for freeway (or for the nutters city) riding. Seems like I don't have to look down for them.
<100 don't matter
120 - I'm keeping up with traffic but a little boring
140 - Must start tucking as my 130 pounds will start edging off the bike
160 - Covering good ground, smooth sailing, reasonable distance to make judgements and I feel nice and relaxed. Contemplate running if I see lights.
200 - Dotted line is now a straight line
>240 - Better hope you have tunnel vision and it's a clear road. Don't feel comfortable at these speeds for too long.
You guys have similar numbers?