I did this trip four years ago and spent a lot of time on Verona forums as well as Just You forums to find out about the best way of seats. I decided not to upgrade from the basic steps, although it would have meant those that did upgrade went and had a meal beforehand, whilst we went straight into the arena and waited a couple of hours for the performance.
One thing I did find out and it was so useful. That is when you get up the steps, dont take the seating behind you but take the row below the walkway. That way you have somewhere to rest your back without other legs pressing into your back. If it doesnt seem clear now, it will when you get there. Most people bought cheap cushions outside the arena but I also took a camping cushion (which I used for my back) and rented a seat cushion from the sellers inside the arena - they were much firmer than the flimsy bought ones and you didnt feel the heat from the stone steps.
Some people dressed up for the occasion - I didnt as it was very hot and I wore my usual cargo pants and smartish t-shirt. The locals didnt dress up and the local ladies in my row put on their flip flops when they sat down. Dont wear flimsy sandals to go there, as the steps are quite hazardous, especially when you come out in the dark. A small torch is useful for that and also I took opera glasses (I think they also rent them) which was great to watch the people coming in to the smart seats below - so many of the couples wore colour co-ordinated outfits and it all added to the fun during the long wait. Lots of drink and food too! I saw Nabucco - dont know what you will be seeing. A fantastic occasion. Lucky you. Hope this is useful.