For alternatives:
* Alternatively: This is a good choice when you are presenting two or more options.
* Otherwise: This is appropriate when you are suggesting a consequence if a condition is not met.
* Rather: This can be used to indicate a preference or choice between two things.
For conjunctions:
* And/or: This is a more formal way of expressing the choice between two options.
* Either/or: This is used when only one of two options is possible.
For expressing a choice:
* Choose: This is a more formal way of stating a choice.
* Select: This is another formal word for "choose."
Example:
* Informal: I want to go to the beach or the mountains.
* Formal: I want to go to the beach alternatively, I would like to go to the mountains.
Ultimately, the best word to use will depend on the specific context and the desired level of formality.