Here you go Polly. This one is not designed for senior execs but it includes things that should probably be in all contracts.
Termination of your employment without notice:
You agree that [Employer] may terminate your employment without notice in the event of willful or serious misconduct on your part, which includes, but is not limited to, theft, fraud, misrepresentation, dishonesty, assault, drunkenness, or being under the influence of illicit drugs, refusing to carry out a lawful and reasonable direction or serious breach of our policies.
Termination of your employment on notice:
Subject to this contract, either party may terminate your employment with [Employer] at any time by providing the other party eight (8) weeks notice in writing of the termination date. [Employer] may, at its option, make payment in lieu of notice for part or all of any period of notice of termination.
We also have a bunch of other clauses which relate to Termination, such as Set Off, Return of Property and Information, and Restraint.
For senior execs you may want add a clause relating to "gardening leave", and there may be other things.
Needless to say, it might be wise to get your lawyers to have a look at the final draft