101 travel rules and pieces of advice :

- Never put expensive valuables in checkin luggage (in case they are lost, and unless you have declared their value and paid a premium to the company to insure them above the airlines' limit of liability).

I would have put the suit and the dress in separate carry on, propertly folded, considering their value... not only because it could be lost, but even if it doesn't, you'll never know if something would not spill and damage your suitcase. A friend of mine experienced this. He also travelled for a wedding with a very expensive tuxedo. A bottle of wine broke in another bag most probably next to his, and upon arrival, he discovered the disaster on the luggage belt... with a grey fabric light suitcase turning red and everything in it.


- Never put any important document (passport, driving licence...) or any mean of payment (CC or cash) in checkin luggage

Other members have already well summarized the situation: EU261 only applies to cancelled/delayed flights, not luggage. There are plenty of topics regarding delayed luggage, you'll find tons of relevant info on the forum (what to do, what you can buy).