Spend attention first
The most personal part of a date is usually evidence that you know each other. Their favourite simple meal, a walk they mentioned or an hour without distractions can mean more than a fashionable venue neither of you particularly likes.
Three entirely respectable proposals
Cook together with a playlist you both enjoy. Pack a flask and take a familiar walk at a quieter time. Or create an at-home cinema evening, including the snacks and the washing-up afterwards. Pick the plan together if a surprise would add pressure.
Handle the logistics
Check the weather, availability and any caring responsibilities. Stay within a budget you are both comfortable with. You have not really planned an evening if your partner has to arrange every detail needed to make it happen.
Leave room for real life
Someone may be tired. A plan may need to change. Flexibility is part of thoughtfulness, and money already spent is not a reason to demand enthusiasm. There is no required romantic ending.
The distinction-level move
Remember what they enjoyed and use it next time. Consistent small acts tend to be easier to sustain than one spectacular gesture followed by a long period of self-congratulation.