We booked for 6 nights but ended up staying for 7. Booking online a week before they only had the smaller rooms available, the 12sqm streetside 'Sugar & Sweet' (http://www.hotel-dellago.ch/E/sugarsweetE.html) was lovely, pink & cosy for the first 6 days. The lake view 'Art & Deco' room (http://www.hotel-dellago.ch/E/artdecoE.html) perfect for our last night. They have reduced rates for 6+ day stays.
Actually, we realised that we'd never have left the hotel if we had one of the lake view rooms - so, a blessing in disguise, perhaps!
There's a wonderful, fresh, expansive breakfast buffet every morning on the deck overlooking the lake. And if you do end up hanging out at the hotel during the day, the decks are closed off just for hotel guests where drinks and snacks are freely available.
At night the bar and lounge area on the lake is a perfect way to end your day, music, great cocktails and our favourite "one-stick" snacks. Friendly barman Stefano made us wonderful drinks on the one night of good weather we enjoyed - they don't open if it's raining, but you can still sit on the covered upper restaurant deck if it's closed.
The Dellago is great value too - after you've been around Lugano for a few days, you realise that it's not a cheap place, most meals for 2 will come to at least CHF50. So, if you factor in having breakfast included, a free minibar (no alcohol, but bubbly water, coke, red bull, tonic, bitter lemon) and a coffee machine in your room when looking at the Dellago's rates - there's at least CHF50/day of value right there. You get all the usual stuff: internet, tv, dvd, hifi, ipod hookup, computer/printer in the lobby.
Dellago is in Melide, which is about 10 minutes drive from central Lugano, so we did rent a Smart Car on our first morning from Sixt (CHF350/wk). There are plenty of trains and buses, but to give you flexibility of getting around it's probably a good idea. Plus there's free parking at the hotel. We managed to squeeze in 900km of driving around, including Lake Como and Interlaken during our 7 day stay.
We didn't eat a full meal at Dellago's restaurant in the evening, but it was busy most nights. This was perhaps the only reservation I had about Dellago, the menu reads a little too complex/fusion for the surrounds. We had drinks and snacks one night where the 'Deep Fried Asian Delight' included guacamole(?!). Having said that, you can't fault the venue for it's views, staff and atmosphere.
All the staff (Karin, Barbara, Nancy, our 'Indian' and the rest) are amazing. The hotel is small but perfectly formed. Not much more to say, it was one of the nicest and relaxing stays we've had. Highly recommended.
Oh, don't forget to visit Alessandro at Osteria Penel for the best meal in town http://www.tripadvisor.com/Restaurant_Review-g188095-d806387-Reviews-Osteria_Penel-Lugano_Ticino_Swiss_Alps.html -- great value too, dinner for 2 with wine (and multiple desserts) for CHF100.