Bike box works just fine, I used one a few times with no problems.
To fit the bike in in, you will need to take off your front wheel, take off pedals and turn handlebars. You also need to protect your fork and derailleur. I usually attach all small bits to the frame with zip ties, so nothing gets lost in case the box is opened or ripped.
If it's your first time, I would ask at LBS how much they charge to box a bike for travel and if they can show you how to do it, so you can box it properly on the way back. I think it's worth the money. If you have a relationship with the store they may do it for free.
Also, make sure to call ahead for a box at both destinations, sometimes they just don't have any.