I had everything developed and about 10 habitats. 1 million gives you enough to build it all over again, but than just as you want it. Don't just close thezoo, delete all paths while the guests are still on it. That teleports the instantly to the exit of the zoo, saves you a whole lot of time and money.
So my strategy is:
1: Keep on going until everything is developed from the mechanic branch.
2: have enough to build it all over again, but that 10 times better and exactly as you want it.
3: Don't worry about your animals. They will all fit in you trade storage, even if you have a 1000.
4: Start slow, and don't open until all animals have habitats again. That way you don't have to lower your entrance fee.
This is what many do when they are bored of their current layout, and are full ideas for a new zoo. Don't close your old zoo, just rebuild it with the knowledge you have.