I think the option of building/upgrading one building and also researching a tech at the same time is great.
I would like to suggest that if a player has the funds and resources available, that he/she can place in the 2 queues more building/tech requests.
To clarify, NOT to have more then 1 building upgrade active at once and NOT to have more then 1 research active at once... simply to place more in the queue behind them if that player has the funds/resources to do so.