Parking in the Disneyland parking lots is $7 for cars, $8 for Autos with Trailers / Campers / RVs / Limos and $9 for Buses / Tractors. Overnight parking is not allowed. Parking at the Disneyland Hotel and Disneyland Pacific Hotels is free for three hours with each validation (purchase required). You can get up to two validations but they must be from two different locations. The two hotels share parking, so if you enter at the Disneyland Hotel you can still get validated at the Disneyland Pacific Hotel and vice-versa. Without validation parking is $2 per hour or $10 per day if you're staying at one of the hotels.
Disney Hotel Resort guests now pay a resort fee of $5.75, and parking in the self-park lots is included in that resort fee. This policy just changed this year.