All intra-Europe flights allow only 20kg of checked baggage per person!! Compare this to 2 bags at 32kg each on a transatlantic flight. If you travel light, then no problem, but if you have more than 20kg (around 44lbs), then you'll have to pay hefty extra-baggage charges. This applies to budget as well as "regular" carriers.

Inconveniences of air travel - vs train travel - include treking all the way to the airport (god knows where for the cheapies) standing in line to check in, going through security, waiting around interminablty for the (often) late flights and then repeating the process at the other end. Never mind dealing with luggage - if they let you have any (my elderly parents seem to travel with 1/2 of what they own.)

With a train you're in the center of town - just grab a cab to the station, walk to the train and get on. No lines, no waiting, no tekking all over hell and gone. And you can get luggage help at most major stations.

Obviously cheaper airlines have a lot of benefits - but they are IMHO not great for elder travelers who have limited energy and mobility.