Welcome to posting, rolshan. Here information I've collected about top European Hilton properties.

London – Waldorf Hilton - the Art + Tech rooms are very cool with nontraditional art and lighting, plasma TV, and showers with 6 vertical shower heads in a translucent enclosure.

London – Trafalgar – W-esque in the heart of London

Hilton London Canary Wharf - a very pleasant surprise compared to the let-down of most London Hiltons

Conrad Mount Juliet, Williamstown, Ireland - one of the best Hiltons worldwide. particularly if you are staying in the main house.

Lyon Hilton – solid

Hilton Evian-les-Bains – beautiful lake views

Dresden Hilton
In the heart of the old town, staff goes out of its way to provide service. Some of the rooms overlook the cathedral, recently rebuilt for its 600th anniversary.
Convenient location, good lounge, modern rooms

Hilton Berlin.
Not only will you most likely get a room overlooking a marvelous cathedral, the rooms are fantastic, the beds super-comfortable, the lounge / piano bar cozy and inviting, and the hotel is right on top of a subway station. You can't beat the location for convenience to shopping, restaurants and nightlife

Cavalieri Hilton, Rome

Sorrento Hilton

Venice Hilton

Hilton Dubrovnik - location is great and everything is very new. lounge balcony has superb views and is a great place to have breakfast.

Budapest Hilton
Fantastic view overlooking the Danube and St Stephens cathedral..

Budapest Westend
Better Executive floor/lounge than Budapest Hilton as well as having free internet

Hilton Prague
which has one the best Hilton lounges in Europe

Hilton Warsaw

Bucharest Hilton

Copenhagen Airport Hilton - brand spanking new and stylish with Bang & Olufsen electronics

Hilton Istanbul – contemporary design

Conrad Cairo

Athens Hilton

With a family of 5, you'll be looking for two rooms. If you have a Hilton AMEX card, consider the AXON awards where you get 4 nights for 125K points.