I'd wish to have more options available in contract negotations for managers.
1.) Clubs should try to sign successful managers for the future. For example if Ottmar Hitzfeld is retiring at Bayern after the season Bayern should watch out for a replacement for him early on the ongoing the season.
Then they would for example offer Thomas Schaaf (manager of Werder Bremen) a contract for the next season.
Or if a manager doesn't completely fulfil expectations at his team then the club should also be looking to get a replacement for him FOR THE NEXTT SEASON as soon as possible.
As it is right now in the game if Alex Ferguson would retire at ManU on June 30th then they would look for a replacement from July 1st on. IRL a replacement would be signed much earlier to make sure that the future of the club is in save hands, new signings can be planned.
2.) Certain managers should have favourite staff members to work with them. IRL many managers ALWAYS work together with the same staff. When I negotiate a contract with a club I'd like to be able to demand certain staff members to be signed alongside me. Otherwise I won't sign.
3.) While negotiating a contract with a team for the next season I'd like to be able to give my potential new club a list of players they should try to bring in for me.
Then the board members would argue if these transfers would be realistic, possible for the club or not.
Based on their reaction I could decide whether I want to sign with the team or not.
This would especially be helful for the signing of players who are available on a free that I want to bring in for my future team.
4.) Discussing a short- and long-term strategy/ objective should be part of manager contract negotiations. Short term objectives would be to stay clear of relegation for next season for example. Long-term would more be about the team's philosophy as constantly building up young home grown talent or bringing in a world class player every season.
5.) Options to extend a manager's contract. For example if I sign a two year deal it could be including an option of an automatic extension for another season if I my team reaches a Champions league spot in the last year of the contract.
Or just "normal" club/manager options that allow to extent the contract at any time.