Tip 1: Do not try to do everything. Think in terms of one quality excursion per day and "milk it." For instance, perhaps you pick one museum (if in a city) or one trail (if in a nature setting). If possible, utilize public transportation to get there, or walk slow. Talk about little details and just function "slow-mo." Your toddlers will pick up on your relaxed attitude, and the lack of a deadline will let the day unfold.
Start a travel journal for a toddler.
Since they can not write, you are going to be the administrative assistant! Collect fun things from each days' adventures - napkins from restaurants, leaves on the ground, maps and brochures. In the evening, while winding down for bedtime at your accommodations, take 10 minutes to talk about the day and let the kids gather their funny collections of scraps. Ask them what was fun about the day - and write it down. Journaling will provide a much more personal approach to collecting memories - in addition to your album of cell phone pictures.
Not to mention, it is a great "show and tell" item for daycare and preschool.
Bring a backpack filled with travel activities.
Never underestimate what a variety of coloring books, crayons, pencils, picture books, healthy snacks, stuffed animals, and a travel pillow will do for a long plane ride. A quick visit to your local dollar store will work wonders! The more goodies you can pack, the faster that flight goes.