If you are looking for an arcade, there is one right by Gasparilla's at the GF. No need to go to the contemporary for an arcade. The grounds of the GF are lovely. Your son can play on the beach, or just enjoy walking around; maybe even take a walk to the Polynesian. There are shops to browse on the 2nd floor of the GF. I think a 19 month old can be entertained on the GF property. Riding the monorail is of course an option but my son never got much entertainment out of that and it does involve going thru bag check, stops at other resorts, packed train cars, etc. Every child is different of course, but my 2 yr old son would often say he wanted to get out after being on the monorail on a short time. I'd take your DS to Gasparilla's for a Mickey waffle, then hit the arcade next door and when finished, just explore the grounds of the GF.