For abundance and extravagance:
* A feast for a king: Implies abundant food and drink, exceeding what is necessary.
* A jewel-encrusted crown: Represents extreme wealth and luxury displayed in a decorative way.
* A boundless ocean: Highlights the vastness and seemingly endless supply of something.
* A garden in full bloom: Evokes a sense of beauty, abundance, and excess in natural elements.
For generosity and giving:
* A overflowing cornucopia: Symbolizes a source of abundance and bountiful giving.
* A raincloud showering blessings: Illustrates the generous and plentiful distribution of something positive.
* A flowing river: Represents continuous and ample provision of something needed.
For impressive and grand:
* A towering cathedral: Emphasizes the impressive size and grandeur of something.
* A majestic mountain range: Evokes a sense of awe-inspiring beauty and scale.
* A firework display: Highlights a dazzling and spectacular spectacle.
The best analogy for "lavish" will depend on what aspect you want to emphasize.