Bridge & other card games/3 spades or 4 spades
In first seat not vul, opposition is vul, should I open the following hand 3 or 4 Spades ?
Q J 10 9 8 5 4 2
J 3 2
At favorable vulnerability I would open the hand 4S and I would guess that most players would do the same. While partner could come down with a hand such as x, KQxx. KJxx, Kxxx which could prevent the opponents from having a game while still leaving you to probably go for 500 in 4S, that is a pessimistic point of view. Even if this is the case, the opponents still would need to guess right to double rather than to bid on themselves and that is not always easy to do. At this vulnerability I would just bid 4S with my eight card suit and let the opponents try to figure out what to do starting at the five level.
If you just bid 3S and the opponents bid 4H, would you be happy letting them play there? I'd guess probably not. So just open 4S and get it off your chest. Furthermore, bidding 3S gives them the opportunity to play in 3NT.