I have visited this holi and religious place twice in life and both the experience was awesome. The site seeing are fabulous with holi ganga river flowing through the heart of risikesh. It is a great place to visit for summer vaccation and also for the hindu pilgrimage.
Accommodations are no problem as their are lots of hotels with variation in range of price can be easily available at any time of the year. And transportation wise its really good, u can even rent a car or a scooter to sight seeing, there are lots of shop which give them on rent in a fair prices.
There is also a great plateform for adventure sports like river rafting, bungee jumping and theres many other. I did rafting.And finally dipped in the holi ganga and washed my sins. : )