What do you think? Help me review my travel plans for backpacking this Fall:

Anything can be done I supposed. I myself tend to move quick and bounce a lot while travelling.
Please consider that it is very likely that in 3 months you will experience delays with trains, buses or flights. So I am not sure when you say 2 days in Seville...do you account for the travel time? If so, you would not have a full 2 days there for e.g.
And moving a lot, usually cost more of course. I have rarely purchase train tickets in advance, in some cases depending on the country you can get better prices but for others price do not vary. You need to check for these.

Is this in order? I am not sure if I would have placed 2 days in Monaco there. Personally, I was fine with a day trip there from Nice (which I loved).

And have you ever done such a trip? I find that busy trips are OK if you have travelled before and enjoyed such a trip and know what you are getting yourself into. Personal opinion of course...

I have been to France, Spain, Monaco and Italy and I am sure you will love them all!
Enjoy and try to learn a few sentences in each language!

I backpacked The Netherlands, Belgium Germany, Austria, and Sweden 5 years ago for 1 month. This is my second time to do a backpacking trip but, I am going for 6 weeks and in the Fall instead of the Spring. Starting north where it will be cool but still not terribly cold and going down south as late October early November arrive. I like fast paced travel and find the "travel" portion to be almost as entertaining as the destination. I also could ditch and stay longer or cut a few places. I am traveling solo and am 26 years old.... I think I can manage.

I'm sure you can manage and I'm sure you will have a great time. I think you can do this -- you may need to adjust a bit to fit the long distances traveled. I haven't traveled by train in Europe for 30 years, so i can't help with details. You're doing a week in the Netherlands, a week in France and larger chunks of tome in Spain and Italy. That can be done.

Way back when....I spent 9 months backpacking around Europe. I spent 6 nights in Amsterdam with day trips to other towns. It's an excellent base.

I would love to see you spend some time in a smaller place in France. You've chosen 2 big cities. You can get to smaller places from Paris, but I think you should look for a smaller base on your way to Spain.

Good luck with your planning

You'll be loosing two very long days on trains going from Spain to Italy with a short stop only in Monaco. If you have no other interest in This area of France this trip, you should save time and catch a cheap Vueling flight from Barcelona to somewhere in Italy.