Hi there, Adriana,
With Disneyland Park and Disney California Adventure Park so close together my family and always find good reasons to hop back and forth between the two Theme Parks. So I understand the motivation to add that Park Hopper option.
To enjoy the Disneyland Resort Theme Parks by visiting just one park on some days and by park hopping on other days, it is possible to purchase multiple tickets. In a scenario like you are describing, one ticket could be a two-day, one park per day ticket and the other a one-day, Park Hopper ticket. Since standard tickets typically expire only once the days have been used up or 13 days after the first use, whichever comes first, it would not even be necessary to use each day of the non-Park Hopper ticket on consecutive dates. (Note: Certain promotional tickets, like the current 2025 SoCal Resident three-day ticket offer have different expiration policies, often with even more flexibility.) If the dates for a one-day ticket are chosen judiciously, it might even be possible for the combined price of the tickets to be less than the price of a regularly priced Park Hopper ticket for all three days.
That scenario highlights the significant added value of a Park Hopper ticket, especially for a multi-day ticket. For example, if you plan a three-day visit and intend to park hop at least one of those days, I recommend starting with purchasing the Park Hopper option. That way, you can enjoy the flexibility of hopping between the parks (subject to park capacity and availability) from your very first day, even if you didn't originally plan to park hop that first day. If you already have tickets without the Park Hopper option, you may visit a main entrance ticket booth at the Disneyland Resort to upgrade any upgrade-eligible ticket to include that option. Since the price difference would be the same whether upgrading the first day of ticket use or the last, I recommend doing that upgrade sooner rather than later to take full advantage of that upgraded benefit.
I hope you have a magical time visiting the Disneyland Resort, Adriana. Should there be anything else we can help with here at planDisney, we are eager to hear from you again.
Have a great day!
~Tony