PokemonGo I have me pokemon storage at 350 and my pokebag at 500.
I wasn't planning on ever upgrading my Pokemon bag and only did so when I was on holiday and went to catch a pinsir but was told my Pokemon bag was full. I upgraded another time while on holiday for same reason as there was so much stuff spawning that my bag filled so quickly and I hadn't had the time to go through everything and see what I wanted to delete because I was either spinning pokestops or catching something.
I upgraded my Pokeball bag before I went away as I'd thought I'd be always full as the place was jam packed with pokestops, in reality the few balls I'd get from one stop were spent by the time I got to another on catching whatever had appeared. Other then my very first night there never came close to filling it while on holiday and when at home 450 is enough for me as I can only take one gym so don't need loads of potions etc.
I had my incense, lure and egg from hitting 25 and as all the lures that were running where amazing I set mine off, and got pidgeys and fucking rats. I still have my egg and incense as I want to make use of that 300 Pokemon storage now I'm home and I'm trying to fill it with pidgeys to evolve.
You could always just hang in to your coins and if you find yourself having to delete stuff often then upgrade it when away, if your bag doesn't get full you could use the coins for an incense to try in a new place. I wish I'd held off upgrading my the Pokeball bag until a stop told me it's full as I'd never have needed to upgrade :)
I'm 60k through the 200k needed to hit level 27, it's taken a about two weeks for me to get quarter of the way through so I'm not planning to hit 30 any time on I'm just plodding along.