For Disneyland/California Adventure park - hoppers hands down! Since the entrances of the park are so close together it's simple to hop between the two parks. They are maybe a football field apart, so you can basically walk out of one & into the other. The non-hopper/one park per day tickets are fine, but in my opinion just require more planning. For example with the hopper passes, if you use your magic morning into Disneyland side of the park, but wanted to see World of Color that night in the California Adventure side of the park, it makes it possible without any worries.
Hi Anna! When purchasing park tickets on our website, getawaytoday.com, you'll want to be sure to put in the general date that you're thinking of going. Currently, we have a spring ticket special that is only valid for admission now - May 23, 2019, with blackout dates of April 14-22, 2019. If you choose to buy this specific ticket, you will have to use your ticket before May 23, 2019.
However, if you're planning on visiting the Disneyland Resort from May 24 - December 31, 2019, your ticket is valid for any day that you choose to enter within that timeframe. Does this help?