If you can keep discouragement from turning into careless eating, you don't have to figure everything out from the start, you just have to start.
There's no magic to either plan, and you can lose all the weight you want to following one plan for the duration, or following multiple plans, alternating plans, etc.
Of the 80 lbs I've lost, I've lost some of it on Atkins, some of it on relatively high carb calorie counting, some of it on South Beach, some of it on Neanderthin, and some of it (my current plan) a low carb, calorie controlled exchange plan (about 1600 -1800 calories). I've experimented (and probably will continue to experiment) with different proportions of the exchanges, for example right now I distribute my exchanges like this 2 starch, 2 milk, 10 protein, 6 veggie, 2-3 fruit, 2 milk, and up to 6 fat exchanges.
I do lose better when I limit my carbs (and I'm less hungry too), but if I want to plan for a high carb day, I just exchange some of the protein exchanges for carb exchanges (in exchange plans the protein, dairy, fruit and starch exchanges have about the same amount of calories).
I have noticed that I can eat quite a few more calories (at least 300) on low carb than on high carb (and am a lot less hungry).
I've also noticed that the more carbs in my diet, the more water my body retains. The morning after a high carb day, the scale can shoot up 5 lbs or more, and it can take a couple days of low carb eating to get rid of that water. This really doesn't impact on true weight loss, but it can be discouraging if you're not expecting it.
A suggestion for mashed potatoes (that the whole family may enjoy) is to combine a bit of mashed potato into cauliflower (my recipe from my blog below)
http://www.3fatchicks.com/diet-blogs...shed-potatoes/
It's not an original idea, there are a lot of recipes (I found out) on the web that combine the potatoes and cauliflower. It's much closer to "real" mashed potato flavor than mashed cauliflower alone, and it's a little higher in carbs and calories but not by much.