Your in a similar position to me with the ages of your kids and there are plenty of family friendly runs around the area 🙂
Refreshment stop at Tayvallich inn halfway around 😉
http://www.forestry.gov.uk/website/ourwoods.nsf/LUWebDocsByKey/ScotlandArgyllandButeNoForestKnapdaleForestGleannaGealbhanArdnoecycleroute
Another..
http://www.forestry.gov.uk/website/ourwoods.nsf/LUWebDocsByKey/ScotlandArgyllandButeKilmichaelForestKilmichaelForestGlashanLochGlashanTrail
The firetower itself is pretty family friendly as alot of it is fire road, so the family can watch dad go head over heels on rough singletrack 😆 or else they can do the cup and rings walk which intertwines with the firetower trail as you have a quick blast on the trails 🙂
Lots and lots of decent walking around the area, as mentioned before the beavers are in Knapdale forest and great fun for young kids (mine love trying to see them!)and they are based at Loch coille-bharr
http://www.forestry.gov.uk/website/recreation.nsf/$$SearchPlacesToGo?Openform&n=&nt=lochgilphead&cr=Scotland&ct=All%20Counties&op=w&g=uaems&sr=
The summer timetable kicks in this friday (26th) for calmac so visiting Islay and Jura is a little easier. Jura would be an excellent day out, also the passenger ferry from Tayvallich starts again on the 2nd of april http://www.jurapassengerferry.com/ which saves the hopscotch from Islay…
Food wise, plenty to choose from now – the Argyll inn in Lochgilphead is worth a visit as it has good beer and excellent food. Horseshoe Inn in Kilmicheal glassary does good food and the kids can run riot as very friendly, also Kilmartin hotel, Cairnbaan hotel, crinan hotel…..
Im based in Lochgilphead so if your looking for more info drop me an email 😉