My 14 year old daughter as expressed interest in going for a longer ride this year.  We have done lots of day trips, some up to 600 miles, but not more than day rides.  I'm thinking 4 or 5 days max, begin and end in SE MN.

Suggestions for destinations that may interest a 14yo girl?

Good riding and some interesting stuff in the Black Hills area of SD. Mt. Rushmore, Devils Tower, Deadwood, etc. Long 600 mile day from SE MN each way each way though. No idea if your 14yo daughter would have any interest in that.

I really enjoyed Devils Tower.

Is she studying anything in school that you could do a history ride?

You don't mention what your daughter's interests are other than spending time with dad.  Which is great by the way and you should cherish every moment.

The great river road to the source of the Mississippi was interesting.

The UP has some natural attractions.

The field of dreams if she is into sports.

Combine the riding with things that really interest her and you will create great memories together.

Thanks for the above posts. 

Her interests are all over the place.  Her main activity is dance when she is with her mother.  With me she likes to ride horses, ATV, and motorcycle, as well as shooting - all which make her mother irritated.  Bonus for me.  Not sure where any of her interests would lead to a destination, other than getting out on the bike. 

As for her topics of study... unfortunately her geography class has been focused on everywhere except the US. 

She will be here visiting this weekend, and I hope to get some more input from her on the summer trip.  We do ride the river (Mississippi) quite a bit since it has nice roads and is near by.  We have never went north of Hastings.I like the idea of South Dakota.  I have a good friend just outside of Custer that has offered a place to stay if we get out there.  Also the UP is high on my list.  Could make it a 3 generation ride with my dad. 

Thanks again.

Ride into Canada and around one or more of Great Lakes. 
On the way there, while in NE MN, tour the abandoned deep underground iron mine (once in a lifetime experience, imo). 

Thank you to all the above. 

We talked over the weekend and have decided on the Black Hills.  Largest deciding factor is we have a free place to stay just outside of Custer State Park with a friend on their ranch.  There is a lot that can be done just day riding from there.  Also some other fun stuff to do at the friend's ranch.  My daughter will enjoy taking up the offer of a horse ride in Custer SP.  Only down side to heading that way is the long boring road to get there.  I'm going to do some checking into secondary roads to see if there is something more fun than blasting down the slab.

I'm sure we will do some riding on the Lake Superior shore too.  Easy to run up there and stay with my parents and/or brother, just a few miles off the lake. 

Excellent! Enjoy!