Suggestions & rambling thoughts for you...

Calendar / Scheduling
Incorporating longer term view of scheduling than just 1 week ahead, suggest monthly? A more extensive calendar would enable much easier planning of nationwide tours longer than 7 day duration without resorting to pen & paper. Still handy to show the current week as it does just now.
+1 to the suggestion of Music festivals, also perhaps Charity concerts where you forgo any payment in return for a boost to band ratings/fans, perhaps would also result in a boost to current album sales due to the publicity?

In game notepad

Map -
Points of interest shown on map, e.g. highlight cities where gigs currently required for record deal, ability to set favourite cities or tour routes
Map pins - click the studio legend buttons to highlight all cities with studios for example

Gigs
Be able to perform additional songs (>5) at gigs which would perhaps earn additional fans / xp at the expense of losing novelty value on those songs.
Gradual improvement to song performance levels through gigs, less than in studio - is offset by the loss in novelty value and could be capped (at say 20%?) but would allow basic proficiency to be reached by normal everyday practice.
Above two suggestions would add some more depth to the matter of choosing a setlist - e.g. do you go for small lists to only barely satisfy gig requirements, minimise loss of novelty value and get efficient revenue.. or longer setlists for extra practice & exposing more songs to your fans to try to gain more following at the expense of losing novelty value quicker on a wider range of your material and not being as efficient at earning money since you only earn the same ticket price for a greater drop in novelty...
Being able to see current band competence when picking songs for a gig would be useful (rather than just song quality) to differentiate between those you have only just written and not rehearsed vs those that are already well mastered.
Autograph signing after gigs - might take additional time (add 1-2hrs onto time), could increase tension (e.g. when your drummer is annoyed that the bassist signs more autographs) but generate extra fans & sales as a result.
Back stage passes - promotional item but could generate random events such as accidentally inviting psycho/stalker type fans backstage, equipment being stolen/damaged, bonus fan-base or album sales

Studios
Change to studio booking where you select just the type of facilities in advance (recording vs rehearsal) and select the songs on the day you arrive there
Additional option for Songwriting activity in studios, (possible boost to either song quality or starting rehearsal % in return for the studio costs).

Own label recording
Would allow you to start with very low quality recordings at mminimal cost before established labels take an interest.
Might lead to being able to buying studio equipment, cd production equipment etc to increase quality & cost savings for mass production.
Lower sales when band is relatively unknown than taking advantage of the distribution network of established labels, but at potential greater reward once sales start to overcome your production costs since you are able to take a much higher % of revenue.
Perhaps eventually other bands might contact you to sign on YOUR label ;) allowing some % of their album sales at a risk of having to pay costs.

Band Merchandise to sell at gigs, online etc - envisage that you select products, choose the amount to place an order, set pricing and then can monitor stock levels. Could tie in with promotional give-aways.

Songs/Album sales & related
Popular songs chosen for Radio play which pays royalties, rights bought for movies & TV themes etc, income boost from cover versions by other artists..
Old Album sales do not remain dormant forever when sales reach zero - continue to trickle sales, spikes in sales due to band activity e.g. gigs & festivals, unlocking new cities
Info about songs when an offer is made - is it currently on an LP for example, what is quality? extra info more than just song title to be better able to decide whether to sell or not. If on an album, perhaps the full album rights could be sold/negotiated? Or album continues to exist, just royalties for that particular song are deducted from income?
Box sets, greatest hits, live albums, special shows could allow DVDs to be made

Miscellaneous ideas
Ability to view band members for hire without firing existing members
Travel costs, increasing band salaries (profit sharing?),
Vehicle breakdowns making it possible to miss gigs
Band members career direction - perhaps they want to do a solo album, makes them unavailable for a set time - maybe they wish to leave the band altogether forcing you to find a replacement.
Equipment degradation & failure, maintenance costs, ability to sell - for props & instruments
+1 hiring of stage crew, benefits for shows & performance e.g. sound/lighting engineers, possible reduced or minimal maintenance costs of equipment by hiring crew with electrician skills
Ability to change the rhythm game difficulty for existing saves

That's all for now, loving the game so far guys!