Hi!
Best Hotels depends on your budget I guess.. I love Costes but it's rather expensive. There is a cool and not so expensive hostel near Crimee (in the North).
Qua sightseeing and attractions:
Skip climbing the Tour Eiffel (it's too crowded) but go see it from the parc and have a picnic there.
The Louvre in the evening is very beautiful, quite, and mysterious, and often there's a guy playing saxophone which sounds great because of the acoustics.
Versailles: not that far from Paris and amazing palace.
Ponts des Arts: during the weekends, but in the holidays also during weekdays, people come here and have their picnic, drink wines, play the guitar.. it's really pretty so Paris from the bridge and it's a great place to go out after (to the left is Saint Germain de Pres and to the right is Point Neuf)
Qua going out in the above mentioned areas, I like maison du nuit Saint Peres in le 6eme Quartier and Le Kong in the 1ere.
Furtermore, I like: Buddha Bar, Experimental Cocktail Club, Duplex (on some nights), Barrio Latino, Showcase, Le Cab, Palais M, Bobin'o, World Place (Manray), Princess and the Frog, Hotel bar in Costes, the Lizard Lounge...
What else would you like to know

?
It's a really pretty city, I like every street and corner in it. It just makes me happy to walk in Paris because it's so beautiful!