First, know that the 2012 itineraries that run thru summer 2012 have been out for awhile so some of the prices have already gone up. You can play around all you want on the disneycruiseline website for prices without actually having to get a quote or book anything. Obviously, the shorter the cruise the lower the price. The more exotic the destination the higher the price. The earlier you book the lower the price. Sometimes they offer special deals like Kids Sail Free but sometimes you must be a US resident to take advantage. You really just need to play around on the website....
Here's a sample of a few Bahama cruises on the Dream for August 2012. I will copy in the cheapest prices from the cheapest avail. category that fits your family for inside, oceanview and verandah. This first cruise is 4 nights. For example in the first cruise below the prices on the inside rooms have risen so much already that the lowest avail. oceanview room is only $96 more for your whole family. For that $96 you would gain a larger SF cabin with a split bath AND a real view with a porthole.

Likewise, the cheapest balcony cabin is only $344 more than than the cheapest inside cabin. It is ALWAYS worth comparing as many scenarios as you can.
Standard Inside Stateroom
Category 11B
Sleeps: 3 or 4
Size: 169 sq. ft.
Deck: 5, 6 and 7
View: Magical Porthole with real-time views
Room Configuration: Queen-size bed, single convertible sofa, upper berth pull-down bed (in some), bath with tub and shower. $3,876.68 View Media Standard Inside Stateroom
Category $3,672.00
Guest 1 Cruise Fare $952.00
Guest 2 Cruise Fare $952.00
Guest 3 Cruise Fare $884.00
Guest 4 Cruise Fare $884.00
Government Taxes & Fees (Cruise) $ $204.68
Total Price $3,876.68
Deluxe Oceanview Stateroom
Category 09A
Sleeps: 3 or 4
Size: 204 sq. ft.
Deck: 5, 6, 7 and 8
View: One large porthole window or 2 small porthole windows
Room Configuration: Queen-size bed, single convertible sofa, wall pull-down bed (in most) or upper berth pull-down bed, split bath with tub and shower. $3,972.68 View Media Deluxe Oceanview Stateroom
Category $3,768.00
Guest 1 Cruise Fare $1,032.00
Guest 2 Cruise Fare $1,032.00
Guest 3 Cruise Fare $852.00
Guest 4 Cruise Fare $852.00
Government Taxes & Fees (Cruise) $ $204.68
Total Price $3,972.68
Deluxe Oceanview Stateroom with Verandah
Category 06B
Sleeps: 3 or 4
Size: 246 sq. ft. including verandah
Deck: 5, 6 and 7
View: Private verandah
Room Configuration: Queen-size bed, single convertible sofa, upper berth pull-down bed if sleeping 4, split bath with tub and shower. $4,220.68 View Media Deluxe Oceanview Stateroom with Verandah
Category $4,016.00
Guest 1 Cruise Fare $1,188.00
Guest 2 Cruise Fare $1,188.00
Guest 3 Cruise Fare $820.00
Guest 4 Cruise Fare $820.00
Government Taxes & Fees (Cruise) $ $204.68
Total Price $4,220.68
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This is pricing for a 5 night cruise in August 2012:
Standard Inside Stateroom
Category 11B
Sleeps:3 or 4
Size:169 sq. ft.
Deck:5, 6 and 7
View:Magical Porthole with real-time views
Room Configuration:Queen-size bed, single convertible sofa, upper berth pull-down bed (in some), bath with tub and shower. $4,254.68 View Media Standard Inside Stateroom
Category $4,050.00
Guest 1 Cruise Fare $1,190.00
Guest 2 Cruise Fare $1,190.00
Guest 3 Cruise Fare $835.00
Guest 4 Cruise Fare $835.00
Government Taxes & Fees (Cruise) $ $204.68
Total Price $4,254.68
Deluxe Family Oceanview Stateroom
Category 08B
Sleeps:3 to 5
Size:241 sq. ft.
Deck:9
View:One large porthole window with seating
Room Configuration:Queen-size bed, single convertible sofa, wall pull-down bed (in most) or upper berth pull-down bed, split bath with round tub and shower. $4,744.68 View Media Deluxe Family Oceanview Stateroom
Category $4,540.00
Guest 1 Cruise Fare $1,455.00
Guest 2 Cruise Fare $1,455.00
Guest 3 Cruise Fare $815.00
Guest 4 Cruise Fare $815.00
Government Taxes & Fees (Cruise) $ $204.68
Total Price $4,744.68
Deluxe Oceanview Stateroom with Verandah
Category 06A
Sleeps:3 or 4
Size:246 sq. ft. including verandah
Deck:8, 9 and 10
View

rivate verandah
Room Configuration:Queen-size bed, single convertible sofa, upper berth pull-down bed if sleeping 4, split bath with tub and shower. $4,954.68 View Media Deluxe Oceanview Stateroom with Verandah
Category $4,750.00
Guest 1 Cruise Fare $1,515.00
Guest 2 Cruise Fare $1,515.00
Guest 3 Cruise Fare $860.00
Guest 4 Cruise Fare $860.00
Government Taxes & Fees (Cruise) $ $204.68
Total Price $4,954.68
Note that the 5 night price for an inside room is only $382 more for the extra night. That is TOTALLY worth it IMHO. I don't find I need a balcony but I DO like a porthole. How much you spend is sort of up to what you want........