For DLR trips I've taken, i tend to purchase / book the various required elements myself seperately.
Sometimes if I find a good deal through Travelocity or CheapTickets I will book a flight and hotel together, but often I can find better options that suit my tastes by booking separately.
An example of my typical pattern for booking another California excursion to Disneyland -
Search flight pricing and options through Travelocity, Kayak, and more recently the 'Hopper' app for the planned dates.
If I like the price, and the flight times, I will book direct with the chosen airlines own official website.
I never book a flight direct with a travel site.
The 'Hopper' app is a great tool for setting up alerts that will make you aware of price drops or expected rises.
Very insightful and handy.
Recommended. ( free app via iTunes )
Next, I typically do a search on those same travel websites for hotels, checking current pricing of favorite spots.
Again, if I find something I like and the price is right, I will book either directly with said hotels' official website or sometimes with the travel site.
I would also often do a quick Google search for favorite hotel discount codes and use them when booking directly through the hotels website.
Another advantage of not booking through a travel site.
If a travel site I'm searching on is offering a 'package deal' ( hotel and flight combo ) I will look over those options.
If you can find something that works for you ( flight times /choices can be a challange here ) consider booking it through the travel site.
You will often save $100 or more doing so.
Read ALL fine print however...be sure there are no hidden fees ( airline baggage fees, crazy 'resort fee' add ons, etc. ).
Both Travelocity and CheapTickets are pretty clear and show any restrictions.
One downside to booking a package is you must pay in full when you book.
If you are only booking a hotel, you pay a deposit ( usually the price of one night ) and the rest you will pay upon checkout.
Another reason I often book things seperately....a bit easier on the wallet.
Next up is Park Tickets.
For a few years, I had a active DLR AP so didn't need to consider adding on admission.
The years I was not, I would buy tickets in advance through the official Disneyland website and have them mailed directly to me.
Any issues, and Disney has you on record and it can be resolved at the Park Ticket Booths.
Others may suggest buying discounted tickets from travel services online, but often what is sent to you is a voucher you have to exchange at the Ticket Booths before you can enter the Park.
I am leery of 'electronic tickets' and 'vouchers' so in my opinion it's buyer beware.
The slight discount , to me, isn't worth the possible issues that might arise.
I always buy tix for DLR direct from Disney.
Hope the above helps you decide how you would like to make arrangements for your upcoming visit.