We enjoyed our stay at Karin's apartment. It's a comfortable place to stay and it's easy to have towels and linen provided.
If you take the metro station Jourdain, you'll pass the café Les Rigolles. This is definitely worth a visit: tasty cocktails and meals at reasonable prices.
We explored Paris with our 7-year old daughter and we enjoyed every minute! There are so many interesting things to see. Le cité des sciences in La Vilette is a good idea if the weather is not that great.