Getting to Disneyland Paris isn’t actually too difficult. Once you arrive in Paris, this basically involves finding your way to the RER-A4 train line. The RER is a regional train system that goes through Paris as well as the surrounding suburbs. A4 is the specific line you’re trying to find. Make sure you get the A4, not the A2 train, as this refers to a specific branch of the A line that will take you to Disneyland. There are many good resources about the specifics of getting around, including the two guides I mentioned previously. Your destination for Disneyland Paris is Marne-la-Vallee/Chessy.
When you arrive at the train station and exit into the plaza, you are actually RIGHT in the heart of the Disneyland Resort. To the north is the Disneyland Hotel and Disneyland itself. To the west is Walt Disney Studios. South leads to the Disney Village Marketplace and the rest of the Disney-owned hotels.
Should you be a supremely lucky individual, your hotel is the Disneland Hotel, and you can’t miss it. It is literally the front gate to Disneyland. Just go through Security and towards the front gates. I am confident that even the most directionally-challenged individual will find themselves in the right place.
Guests of the New York Hotel, the Newport Bay Club, or the Sequoia Lodge have to go a different way, but it is still within walking distance. If you find yourself on the World’s Longest Moving Sidewalk because you were foolish enough to follow the signs to your hotel, sadly you are headed the wrong way. And you will continue to head the wrong way for quite some time, so get comfortable. After an eternity you will arrive at the parking lot and bus pickup. Turn around, grab a drink from the vending machine if necessary, and start the round trip back to the plaza.
Eventually you will arrive back where you started. Now this time, IGNORE the signs directing you to your hotel and head through the security checkpoint toward Disney Village. Walk all the way through, and when you come out the back side you will be next to the New York Hotel. Around the small lake found there, the Sequoia Lodge and Newport Bay Club are also visible, but a bit further walk.
The Hotel Cheyenne and Hotel Santa Fe are both technically in walking distance, but it is a bit of a hike. The World’s Longest Moving Sidewalk will actually take you in generally the right direction, plus save you some walking at the same time.
If you’re staying at the Davy Crockett Ranch, you must catch a shuttle bus because it is actually a fair distance from the main resort.
One last thing you will notice as you traverse the security checkpoints is that they are run differently than the parks in the US. In Paris they utilize x-ray bag scanners like at the airport, rather than manual bag searches. The process is actually quicker (in our experience at least) so the line moves at a reasonable pace. Disneyland, Walt Disney Studios and the Disney Village are all part of one large, continuous security zone so you can walk between any of them without going through security. The hotels, train station, and the rest of the world are not, so plan to go through security if your origin is one of those three places.