We have flown many times with our little guy who is now 16 months old. Here is some advice I have to give:
1) Bring your good stroller (Sorry but I don't think it was a very practical suggestion from the mother who said to ditch the stroller. Traveling with an 11 month-old is VERY different than traveling with a 2 month-old) - it might be a little heavier and bulkier than the umbrella stroller, but you will want it when you are walking in the airport or when you arrive in Europe...it will give you the storage you need for your bags, let the little one sleep in there (I'm assuming yours reclines), and if you have a treat tray, even better for snacks or meals on the go. Not applicable so much now, but during the summer months for traveling, the bigger strollers have better sun shades, too.
2) Purchase earplugs. Walgreen's sells these for pretty cheap - they come in a clear plastic case, and the ones we've used are bright orange - they are waxy and moldable -you break them in half and use 1/2 in each ear. These are a MUST if you guys want to stay up late with the wedding party or have later dinners after the little one goes to sleep. When we travel, we always get him to sleep, put the earplugs in, get him cozy and recline the stroller, and we're good to go. Make sure you remove the earplugs at the end of the night when you transfer her to bed though, so she doesn't find them in the morning and try to taste them!
3) If your baby has seen/likes any movies like Baby Einstein, you can purchase a tiny portable DVD player and take it on the plane. This has been a godsend for us when he's tired of the trip - chills him right out for about 20 minutes, then we can read more books or play with toys some more.
4) Stash some plastic bags in your diaper bag for diaper changes you might need to make on the plane, and just to have a little trash space.
5) Make SURE you have something to drink and/or a pacifier ready to go for take-off and descending. Their little ears can hurt them miserably, and the sucking motion will help relieve that pressure.
6) Don't forget the wooby, fave toys, or anything else your baby can't live without. Try to stagger letting her see the toys you brought so it keeps things fresh and interesting for her. My little guy loves having sets of things, so I always travel with little stackable colorful cups or baby spoons. These are fun to count, chew on, and countless other imaginative games!
Best of luck and have a great time!!