The most I have been on my 250 in a day has been just short of 200 miles. I would take a break about every hour or so. I was pretty comfortable.... but then again I have been known to sleep on bare floor. As far as speed goes, the 250 will accelerate faster than most cars on the road.
The longest i've ever rode my bike was from Fresno to Merced, about 1 hour. in that one hour, my butt was hurting because i sat too long (but i have a skinny butt). The ride was smooth and YES you can go over 70MPH. i can't stand going slower than 85MPH. the fastest i've gone on the bike is 107MPH. I also lowered my bike and did my own little exhaust mod. When i have time i'll put up a post with pics. I just drilled holes in the exhuast to make it sound louder but i felt that it gave me a bit more power too.
I'd add that you can do things like get in the gym and work out your gluteus to make sitting more tolerable for longer periods of time while riding but that most likely you'll be looking forward to those gas stops on longer rides.
I took the bike on a 200 mi ride and my knees hurt a bit at the end, but I'm 6'2" so that may contribute to it... but hurt a little, but we did stop a few times. I can also attest that it is more than capable on the freeway.
I recently took a trip to nags head. My riding buddy and I fooled around a lot in Virginia before we crossed the boarder, but all said and done, we rode 417 miles that day. My knees did ache a little, but I cured that by sliding my foot forward on the peg. I usually ride with the ball of my foot on the peg, but when I slid my foot forward to about mid foot, i noticed my knee started to feel a lot better. My backside did get a little sore, but frequent stops (and stoplights!) helped.
After a couple hours in the saddle I was wishing for an aftermarket seat! No problem with speed though. It'll go 90 all day long if you want it to and if you keep the revs up between shifts it will take off and reach cruising speed as fast as almost any car on the road.
ive rode from Kennesaw/Atlanta Georgia to greensboro NC on my ninja and ive gotten 280 miles off of a full tank of gas.. which is like about 75 percent of my way there and about maybe 15 dollars premium gas.. id say its a comfortable bike but if you do long term riding you will start to sit againts the tank for a little when your about 70 percent through your trip if you did the same..
It might have been because when I first rode, I did not have my clutch in the right position. I somehow pinched a nerve in my hand, if that is possible and for that year (2008) my hand tingled and went numb.
However after adjustment I went around 100 miles from Mastic Beach to Long Beach. The only thing was my hands from the vibration. Not sure if it is because the first year I held on too tight and that wrist clutch thing messed up my hands nerves permanently?
I've been off the road since then and DMV says I can finally ride in August so I'll know then how my hands are.
Does any of you have that issue? Oh my butt aint too bad. Sometimes I'll raise my butt up in the air for some comfort when I feel it getting a little flat