Last time we went DS was 2 and 1/2, it was the 4th of July weekend. We took our britax umbrella stroller and purchased several travel accessories.
The good:
A Rayshade, which turned out to be an excellent investment since it not only shaded DS from the sun while he was awake, it was big enough to stretch and pull it over enclosing the whole front portion of the stroller for naptime. We could also fold the stroller with the thing still attached.
A stroller cooler (JL childress), which was a great place to store cool drinks and snacks (instead of a parent console),
The bad:
A stroller fan, which was a waste of money. DS thought it was a super cool toy, and broke it within 20 minutes by repeatedly putting his finger on the fan to stop it.
Several kind of toy/cup tethers, another waste, an invitation for items to be thrown to see what happened. They did help us identify our stroller though. We just avoided giving him anything but water while on the stroller.
A cup holder for the sippy cup/snack cup (brica snackpod), another waste, it kept the stroller form folding properly, so we had to remove it every time we folded it. It also kept falling off.
A Rain cover, I think having one is a good idea, but we got the Jeep standard weather shield and it was a piece of $@#. DS got soaked from the waist down. Thank God he thought it was hilarious as opposed to having a meltdown. We ended up using a disposable poncho after the first rain. So either get a good quality one or use a poncho.
The stroller basket was big enough to leave a diaper backpack with change of clothes and other necessities, like blanket, diapers and wipes and a few other things. I wish I had a nice cupholder for myself, but to be honest reaching down to grab a drink from the cooler wasn't that much effort.