For me, it all depends on how badly I want to get somewhere vs. cool things to see. Living out west there are large areas of nothing so at times I will easily do 4-450 in a day, other days with sight seeing maybe a couple hun.
Depends on the Road and journey. Running down the coast Hy-way, 250 miles is a day and it beats you up. Running the open roads like I90 Through Montana to S Dakota 500-600 is a fun day. A rule of Thumb for Me and Wife on the back is 500ish per day.
While on a trip how many miles do you like to run down in a day? I am hung up on 300 max. a day, never really do much more, what say you?
Hell I go 400+ round trip just to have a burger with friends.
As for a trip every time I go visit a friend of mine I plan on stopping in El Paso (550 miles) but I usually get there about 3 in the afternoon so I just keep going thinking I'm gonna stop soon until eventually it becomes 'I might as well go on to his house as I'm too close to stop now'.
Last time I checked my trip meter it said 918 miles door to door.
Depends on the roads. If I'm going to Nashville to see friends, I'll make the trip straight through all I30/40 and rolling. If I'm running around sight seeing in the mountains, 350 is pushing it.