Tower Boat

Tower Boat
I land at CDG Paris at 8 AM and catch a flight back at 7 PM, best way do HOHO bus tour and boat ride both th?

Want to do on a budget. My wife accomanies me. I think RER to Gare du Nord and bus tour from there. Boat from Eiffel tower and back to CDG. Please give details of routes for train and bus.

To get from CDG to Paris, the RER B goes directly to Gare du Nord (and into the city) and it's normally 8.40 euro one way, for adult. You'll be doing at least 2 RER journeys that day (one from airport, one to airport) so you should consider getting 1 day zone 1-6 Paris Visite pass which is 18.50 euro (http://www.ratp.info/touristes/index.php?langue=en&rub=decouvrir&cat=paris-visite&page=tarifs ) and which this is a bit more than simple 2 one-way tickets to/fro airport, but it is worth considering because it has other discounts and advantages.

Paris L'Open Tour (http://www.pariscityrama.com/paris-open-tour ) is the only HOHO tour operator that passes Gare du Nord. It runs 4 routes that you can take and swap around with, and the 1-day ticket costs 29 euro per adult. If you decide to get the Paris Visite pass, then it's 25 euro. The Paris L'Open Tour link above has the route information on the routes that they run. You can also combine Paris L'Open Tour with Batobus and this combination ticket costs 39 euro.

There are numerous boat tour and they in general takes about 1 - 1 1/2 hours. The following listed have starting/ending point at the quay side adjacent to Eiffel Tower (except Bateaux Mouches which is a bit more up the river to the east, by Pont d'Alma):
1) Bateaux Parisiens : 11 euro per adult (http://www.bateauxparisiens.com/EN/offers-cruises-seine-paris/cruise-sightseeing-leisures-paris/sightseeing-cruise-seine-paris-eiffel-tower-prices.html ) - if you have gotten the Paris Visite pass, you can get 25% discount of Bateaux Parisiens
2) Les Vedettes de Paris : 11 euro per adult (http://www.vedettesdeparis.com/52/1/croisieres-vedettes-de-paris-our-cruises.html ) - there's 20% off promotion online at the moment
3) Bateaux Mouches : 10 euro per adult (http://www.bateaux-mouches.fr/tarifs/ )
4) Batobus is a HOHO boat tour : 12 euro per adult (http://www.batobus.com/english/tarif2.htm ) - this tour would take the longest to complete as it stop to let people on and off throughout the route, and there is no commentary.

Given you plan to cruise to/fro Eiffel Tower, and from there, to try to get back to the airport, the metro/RER option that is simple and involves only one change is to take RER C from Champ de Mars-Tour Eiffel (direction : Massy Palaiseau) to St Michel-Notre Dame. From there, change to RER B (direction Aeroport CDG). You should be travelling back to CDG on the RER at 4pm the latest to play it safe, as it takes about 45 mins to get to the airport, and that'll give you enough time for the advised 2 hours prior to flight time to check in again etc.

The costs involved in the option with Paris Visite:
- Paris Visite pass (for use on RER/metro) : 18.50
- Paris L'Open Tour (Paris Visite discount) : 25.00
- Bateaux Parisiens (Paris Visite discount) : 8.25
Total : 51.75 euro per person

Alternative costing:
- 2 single tickets to/fro CDG airport : 16.80
- Paris L'Open Tour + Batobus pass : 39.00
Total : 55.80 euro per person