Sounds like you were using some SEVERELY crippled demo version of FL studio.
Now that you own Sonar just go apeballs however you want but yes... a track is of unlimited length. Use ONE track per instrument and record/program whatver you want into it.
Within the track are "Take Lanes". Each take lane can hold a different performance/recording and will play through the same track. These lanes are comprised of MIDI or Audio clips. You generally only want one lane playing within a track at one time (but with a slight overlap of clips in the lanes with crossfades so the various "Takes" blend nicely together).
So... if you record five takes into the same track they will show up in the take lanes as their own distinct "Lane". From there you can slice and dice/mix and match these performances by using the "Comping" feature or other editing methods inside the same track.
If you are not aware of how to use or access these features just search in the manual for "Take Lanes", "Comping", "Comp Mode", "Smart Tool" and so on. There will be other links/references for each entry that can lead you to other info on this process.
To totally answer your question... I (and pretty much everyone) just record into a track as many times as I want/need to and all those recordings show up as distinct lanes. Once I feel I have recorded enough good/useable takes I start to "Edit" using "Comp Mode". Basically that is the process of going through all the takes I just recorded, finding the best parts of each take then using the "Comp Tool" to "Promote" those parts so they are audible (and everything else that occurs at that point on the other takes becomes muted).
By doing this I create the best track I can out of all the recordings I made.
You do NOT want to stack your tracks like you described for FL. THat is a ridiculous and crummy workflow which you obviously only had to do because of some weird limitation.
There are videos on this site under the CakeTV/Cake University section that show how to do this. I recommend watching pretty much all those vids as well as checking out the manual.
However now that I think of it what you MAY be referring to is the Step Sequencer in FL Studio. That is a completely different subject. Those aren't "tracks". Those lines output to tracks. The Step Sequencer in Sonar will generate "Step Sequencer" clips in the "Track View" that you can then edit, drag out and generally manipulate however you want. You can also convert them into proper MIDI clips that can be edited more precisely in the "Piano Roll View".
These are all topics you should be looking into. I'm just throwing words, names, topics and ideas at you to search. If you are totally stuck in only using the Step Sequencer you are seriously limited within the program.
Yes you can extend the Step Sequence pattern out REALLY far in Sonar but that is not how you want to program MIDI.
Damn... it's really hard to explain in a single post because there are dozens of interrelated topics that need to be understood.
Go through the tutorials at the start of the manual, watch the vids on CakeTV and come back. Those explain a LOT.