I'm trying to understand what to expect when I show up at the gate for budget travel on Vueling or Iberia. For example, Iberia says that the max dimension on a carry-on are 158 centimeters, but in another section of their guide they indicate that there are also restrictions on max height, width and depth. They also have a weight restriction. Vueling just mentions the dimensions (55x40x20 cm) and the 10 kg. rule. Vueling's dimension limits are much more restrictive than Iberia's.
What's your experience been with this? Is it better to buy a luggage check on-line in advance or take the chance that everything will work out at the gate.
Also, how big can your second item be? I've found that a day pack will fit well under the seat in front of me. Is that kosher on Vueling and Iberia?