How about not using them at all? I prefer BTC and I hate that I need to calculate back and forth between different denominations.
yes i prefer to call that 10k satoshi , 100k satoshi than uBTC and mBTC
For real transactions of goods and service (from a cup of coffee to a Lamborghini), I think it is okay to stick with "BTC".
For microtransactions (eg. faucets), I think it is better to use "satoshi" instead of 6 zeros after the decimal point IMO.
If we should indeed go higher when it comes to the Bitcoin price, you wouldn't want to denominate a coffee in BTC anymore! It would cost you 0.00061 BTC or something, people will get really confused by that. Going with bits is the best way to go in my opinion!