There's a really good player review on the Big Fish forum. I will copy and paste it here, as it contains a lot of good information.
The premise is you play as Chloe who hates her boring job and wishes she could live out her dreams. She falls asleep at work to awaken in the Dream world. The Dream world is full of hotels and it’s where we all go when we sleep in order to wake up refreshed and invigorated for a new day. Unfortunately, nightmares have overrun the Dream world and you must help rid the hotels of them so that everyone can continue to have a happy and peaceful sleep.
There are five hotels with 12 levels apiece. Each hotel has a different nightmare attacking it and unique playable areas.
For instance, the first hotel you run has a ski theme. The areas you will play are the guest’s rooms, a ski lift, a fire pit area, a hot tub, and a kitchen or food prep table. The nightmare that attacks in this hotel will freeze the guests into snowmen and they must be clicked on because while they are frozen they lose hearts. If they lose all their hearts, the guest will leave.
As you progress through the levels 1 to 12 in each hotel, you can purchase upgrades for each of the areas in order to make more money. (i.e. the hot tub can be upgraded to include bubble jets and the guests will pay more for this feature)
There are also three mini-games you play interspersed between levels 1-12. They are different from the other upgrades in that they will allow you to expand some of the playing areas. (i.e. you’ll get a second lift for the ski lift area which means more guests can ride at one time)
And here is the spoiler/strategy section from the same player's post, which is also helpful:
Since there is a certain amount of strategy required to achieve expert on most of the levels, here are some tips that worked for me.
I found that if you play each hotel to level 8 regardless of whether you achieve expert on them but still continue to purchase upgrades on each new level then it is much easier to get expert when you replay the earlier levels.
The reason being is that once you beat a level you only accrue more money if you do better on that level then the best time you played it and then you are only given the difference between the two. For example, if you beat level 1 with $2500 and then get $2600 when you replay it only $100 would be added to your total upgrade money.
However, all upgrades you make in the later levels roll all the way back to level 1. Most times you can’t get expert without the areas being upgraded so it’s best to just wait it out until you have them and then replay the levels.
Also, as a warning, the last hotel is quite hard because the nightmare attacking that hotel steals all the guest’s hearts and when that happens they will need to be checked out immediately with no money earned for them.
I definitely had a great time on the final hotel it was just tricky trying to keep an eye out for the nightmare and dealing with a boatload of guests.