dbmet,
I have always liked Jager heaters, they are very reliable. For a 34 gallon I would go with a 125W heater @ $27.99. The 90G would need a 200w heater @ $30.75.

paul,
Your aquarium would probably need a 300w heater @ $35.00. If you want more control over the heater I would recommend a controller. Temperature only controllers are available but I would opt for something with more features, like the Reef Keeper.

Let me know if you have any more questions.

Louis