Hi Iryna! Thanks for dropping by planDisney.
If you're even considering visiting a second park on the day of your visit, I'd suggest purchasing a
Park Hopper. Not only is this a better value than purchasing a second 1-park ticket on the day of your visit, but you also run the sizable chance that
theme park reservations will be sold out for the day. If that's the case, which it often is, you'd be able to purchase a ticket but would not be able to make a theme park reservation, meaning you couldn't actually enter the second park. That would be a very unmagical experience.
There's a lot to do in both
Disneyland Park and
Disney California Adventure Park, so a Park Hopper offers you great flexibility for a 1-day admission ticket. It's what my family purchases on our short trips. We typically start the day in Disneyland Park, eat lunch, and hop over to Disney California Adventure Park. Then, after we finish our to-do list of attractions, we hop back to Disneyland Park for the evening.
I suggest downloading the
Disneyland mobile app prior to your visit. It's a useful tool for planning and being familiar with it helps you navigate more easily once you arrive.
I hope this helps!
Elizabeth