We have stayed at a delux room for three nights. Room was spacious and nice; sparkling clean bathroom; internet, LCD TV. Prices of goods in mini bar very too high...
Not the best layout of hotel itself - many stairs and corridors.
Breakfast buffet could be better: horrible coffee, no wide selection of meats, cheese and fruits. IF you want a real breakfast, order Royale breakfast in your room (15euro). Hotel restaurant is quite good though.
Hotel is connected to Druskininkai city spa, which can be very crowded and over booked on weekends. Unfortunatelly you cannot go to have your treatments in a robe and slippers. No swimming pool on site (there's a small mineral water pool in SPA, but it's not free for hotel guests).
Since everyone comes to Druskininkai to pumper their bodies, I'd suggest to stay in a hotel which has everything on site. Try spa-vilnius.lt for example. Europe Royale is expanding too - they are finishing a new wing, which will have a swimming pool and saunas.