Two days is enough to get a sense of the resorts, but it won't be enough time to do everything (or really even most things). I think guests need a minimum of 3-days to really get a lot of the resorts done or 5-days if they wanted to try to do almost everything (including shows, character meet & greets, etc.). With only 2-days, you'll need to prioritize which attractions, shows, and characters you want to see. I would try very hard to get there pre-rope drop and stay until closing to maximize your time.
It's hard to say which park you'll be spending more time in...it really depends on what type of attractions you like, which shows you want to see, etc. One of the first decisions you'll have to make is whether you want to get park hoppers or not. The two parks are only about 100 yards apart; think of DL like Epcot's FW, DCA like Epcot's WS, and DTD is just outside of Epcot's International Gateway. It's not exact, but it gives you a sense of how easy it is to go from DL to DCA and back. With a two-day trip, I think you could go either way (park hoppers or no park hoppers). Park hoppers gives you the flexibility to jump between parks, go back for attractions you missed or wanted to ride again, and see more than one nighttime show per night (if being presented).
When you are thinking of going in May? There are some events that will increase crowds and may limit how much you can get done. The Tinkerbell Half Marathon is slated for Mother's Day weekend, so the crowds are likely to be high. Memorial Day weekend is at the end of the month and three-day weekends tend to be busy (if there is a 24-hour day on Friday, that can also impact crowds). Grad Nites start in the middle of the month.
In terms of hotels/motels, I would second the recommendation to take a look at the places along Harbor Blvd between Ball Road (or just north of Ball Rd) and Katella (or just south of Katella). Most of those will be within walking distance (I highly recommend finding a place within walking distance to avoid having to drive to the parks and dealing with the parking structure). I like the Best Western Park Place Inn because of the location. There is nothing really special about the BWPPI, but it's one of the two closest motels to DLR. For a higher quality place, I liked the new Courtyard Theme Park Entrance. The hotels down by the Convention Center are nice, but the walk is a bit long and might be outside of some folks definition of "walkable".
Some major differences between DLR and WDW:
- At this point, DLR is still using the "Legacy" FP system. There is no Magic Bands or FP+ at DLR, so you cannot "reserve" your FPs in advance, but for the most part, the FP system at DLR is similar to the FP system that WDW was using before they went to FP+. You'll insert your ticket into the FP machine to get the FP; they do post the current return time so you'll know if it works for you or not before getting the FP. You can also check the official Disneyland App, which will give you the current return time. Unlike WDW, there is no official grace period (either early or late), so plan on returning during the time window printed on the ticket.
- Another big difference from WDW is dining. DLR opens their dining reservations 60-days in advance (approximately), but dining reservations can usually be obtained with just a few days notice. I still recommend making dining reservations if you know you want eat at a specific restaurant or at a specific time, but it's not critical that you be on-line right when the system rolls (which happens somewhere between midnight and 8:00 am pacific time).
- DLR posts their operating schedule approximately 45-days/6-weeks in advance, but entertainment and other daily information may not be added until much closer to the date (usually by the 30-day mark, but not always).
- There are several long-term refurbishments/closures occurring in the park right now. The Rivers of America (Tom Sawyers Island, Mark Twin, Columbia, Canoes, and Fantasmic!) and the Train will be unavailable until sometime in 2017 (most likely) as part of the prep work for Star Wars Land. Over in DCA, the Hyperion theater is dark until the debut the new Frozen stage show on May 27th. The Autopia and Jungle Cruise are currently closed for lengthy refurbishments, but they may re-open before your trip (Autopia has a target re-opening date in very late-April and Jungle Cruise is slated to re-open in mid-May at this point, both are subject to change without notice). DLR doesn't always announce when refurbishments will start or end with much notice.
As mentioned, I highly recommend looking at
HydroGuy's A DLR Guide for WDW Vets to help orient yourself. It'll give you a sense of the similarities and differences between the two resorts.
There is also a
May 2016 Check-In thread that you can join.